Don’t waste your time booking trips on separate airline sites or travel services like Expedia and Orbitz. Fire up Kayak, type in your trip coordinates, and watch Kayak scour them to find the lowest prices and widest selection of hotel rooms, flights, and rental cars. Book online or by phone with the tap of a key. Kayak’s First Class version ditches banner ads on the results pages and scouts for first-and business-class airfares as well.

BOOK ’EM: Tap the appropriate icon in the top row of Kayak’s home screen to search out the cheapest beds, plane seats, and wheels for your trip. The next group of buttons lets you check out the amenities at major airports, track your flights, see how much each airline is charging you in tacked-on fees this week, and save your itinerary to Kayak.com.

PICK A FLIGHT: Once you enter your flight’s starting and ending cities, travel dates, and number of passengers, Kayak’s search engine revs up and collects flights and fares from across the Web. Tap a flight that suits your needs and budget, and Kayak displays its arrival/departure details, along with tappable phone numbers and website URLs so you can reserve a seat.

KILL TIME: If you’ve got a long layover or your flight’s been delayed, tap Kayak’s Airports icon to see shops, restaurants, bars, and other hangouts where you can while away the hours in the airport you’re stuck in—or in the airport you’re headed to on the next leg of your journey. Kayak also shows you local ATMs, newsstands, and business centers.

BOOK A BED: Kayak’s Hotel search rounds up all the accommodations near you (helpful if your flight gets canceled) or in your destination city. Once you get the results, tap the row of buttons at the top of the screen to see the least expensive, nearest, or fanciest hotel rooms. Tap the buttons below the results to filter by price, star rating, chain, and more.

LAND OF THE FEE: Many airlines, especially domestic carriers, now charge for meals, checked baggage, and even in-flight snacks (a practice called “unbundling”). To see what your airline plans on charging you (besides what they already charged you for your seat), take a breath, tap the Fees icon on the home screen, and find your airline in the list.

TripDeck lets you keep all your trip’s vital information—confirmation numbers, reservations, meeting times, notes, and so on—in one tidy place. You can easily email your itinerary to family, friends, and colleagues who may need to reach you on the road, or sync your schedule with the TriptIt website to keep a copy online. Although TripDeck itself is free, the app offers extra features, like flight maps and travel alerts, that cost $4 each.

PLAN AHEAD: Staying on top of your airline tickets and confirmation numbers can be hassle enough, but when you factor in the coordinates for hotels, rental cars, business meetings, dinner reservations, train schedules, and the other minutiae of work travel, you’ll appreciate TripDeck’s organizational skills—it displays all of your info on an easy-to-navigate Quick Reference screen.

SHARE YOUR PLANS: Jam-packed business trips can give you information overload as you try to remember what meeting comes next and where you need to be. Tap an item on the Quick Reference screen (below left) to see just a segment of your journey, neatly isolated on its own screen (below). You can email a copy of that one item—or your entire itinerary—by tapping the envelope button.

Whether you take an annual vacation with the family or hit the road twice a month on business, Packing Pro makes sure you don’t forget anything. Not only does it offer checklists for clothing and toiletries, it reminds you to pack your pills, camcorder, and swim goggles. In addition, its handy pre-trip checklists prompt you to do essential tasks before you leave, like suspending mail delivery and changing your office voicemail.

LISTS OF LISTS: Packing Pro offers a checklist for just about every aspect of a trip, divided into eight categories. The categories themselves have their own subcategories of lists to make sure you don’t forget anything. If you tap Toiletries, for example, you’ll see that topic divided into lists for hair, face, mouth, and body products.

CUSTOM TAILORING: Once you select a list you want to use—Clothes, for example—you can modify it by adding different types and amounts of gear (depending on the length of your trip and how often you want to change). Tap a line item to enter a new amount and to add information like weight and value in case something goes wrong in the baggage area.

The App Store is full of great flight-tracking apps—including rival FlightTrack Pro—but Flight Update Pro edges out the competition with bold, colorful graphics and seating charts for many planes, courtesy of SeatGuru.com. In addition to displaying the current status of your flight, Flight Update Pro shows you gate and baggage-claim info, the local weather, and layover times. If a flight gets cancelled, you can search for alternates.

UP IN THE AIR: Flight Update Pro’s neatly designed status screen makes it easy to see all your flight info, including arrival and departure times and meals available, at just a glance. Tap the Options button to bring up the plane’s seating chart, the local weather forecast, and alternate flights. Tap the Send button to fire off a copy of your status by email or SMS message.

MAPPED OUT: Tap Flight Update Pro’s Map button to see your plane’s position in the sky, plotted on a Google map. Other facts about your flight, like its altitude, speed, and estimated time of arrival, put the plane’s progress in perspective. Have the app update the map at set intervals, or tap the Refresh button to do so whenever you want.

UPDATE YOUR UPDATES: The Prefs button not only lets you set the timer for status updates, it lets you set your preferences for the units of measure you want to use for temperature and wind speed. Like many travel-themed apps, Flight Update Pro works with the free TripIt site so you can store a copy of your itinerary online. You can link to the site from this screen.

HONORABLE MENTION

This rival to Flight Update Pro also does a superb job of monitoring and mapping planes in the air—and those still trying to get off the ground. FlightTrack Pro seamlessly integrates with the free TripIt site, so if you send flight confirmation emails to TripIt, the flight shows up in FlightTrack Pro. The app supports the iPhone 4’s high-res display, so even maps depicting bad weather look great. Don’t have any trips of your own to track? Shake your iPhone to check out a randomly chosen flight.

INFO AT A GLANCE: Add a trip to FlightTrack Pro and you get all sorts of information on the flight, as well as how much time you have to make your connections. The app reveals how late a plane may have pushed away from the departing gate and predicts its appearance at the arriving gate. Tap the airport name to get weather conditions and FAA alerts for that location.

Billboards and blue highway signs list only a fraction of the restaurants, rest stops, gas stations, and other necessities available off of each interstate exit. Fortunately, iExit fills in the gaps, using the iPhone’s GPS to pinpoint your location and show you all the eateries, service stations, chain stores, and more available at the nearest exit. If you’re not ready to stop just yet, the app shows you what’s available an amazing 150 exits down the road.

EYE IN THE SKY: Thanks to the iPhone’s GPS, iExit knows when you’re on the road and when you’re not. It presents you with nearby amenities as you approach each exit. Tap the gear icon to adjust what you see. For example, if you don’t care about diesel gas stations or campgrounds, you can turn those off so iExit doesn’t waste pixels displaying them.

POINT A TO POINT B: When you do find a restaurant, hotel, rest stop, or other establishment worth pulling off the highway for, tap its entry in the Exit list to get more information. The app displays the place’s location on a map, provides a phone number you can tap to call it, and even generates directions from the exit ramp, courtesy of Google Maps.

EASE ON DOWN THE ROAD: You don’t have to wait to get to an exit to see what’s available in an upcoming area. You can browse for potential lunch stops for tomorrow’s all-day drive the night before (Touch users, do your research using the hotel’s Wi-Fi). Tap the book icon to call up iExit’s Exit Lookup feature and find out what awaits you at each exit nationwide.

HONORABLE MENTION

Whether you’re in a car or walking around an unfamiliar town, AroundMe uses the iPhone’s GPS to display a list of area hotels, restaurants, gas stations, hospitals, pharmacies, banks, ATMs, and other points of interest. To get a different perspective, activate the iPhone’s camera and turn the device horizontally. Business names float above the real-life buildings in the app’s “augmented reality” mode, a mashup of what the iPhone’s camera sees and its compass function.

YOU ARE HERE: AroundMe’s breakdown of businesses into sensible categories makes it a great app not only for unfamiliar locales, but for finding stuff right in your home town. When you need to find a gas station to fill up the tank or a nearby supermarket to fill up the cooler for a day’s drive, AroundMe shows you what’s available in the ’hood.

To grab a cab just about anywhere in the world, check out Rocket Taxi’s list of 27,500 taxi companies in 10,000 cities. The app’s database works fine offline, but when you’re online, it identifies your location and suggests local cab companies for your conveyance. The app’s Trip Calculator estimates the fare as you ride along, and the currency converter tells you what your trip will cost in the coin of the realm.

CAB DOOR TO THE WORLD: Rocket Taxi’s extensive listings let you ring up cab companies in thousands of cities around the world with just a tap on the screen. You can review the star ratings to winnow your choices, add preferred companies to your Favorites list, and report outdated information to the app’s developers. If you run into a cur of a cabby, rate him by swiping a set of stars.

CASH CONVERSIONS: Rocket Taxi’s trip calculator displays a suggested route, gauges the distance between your pickup location and your destination, estimates the fare, and converts it to the local currency so you can tip appropriately. Keep in mind that an estimate is an estimate and may not account for local surcharges or cabbies forgetting to change zone information for your ride.

HopStop’s iPhone app is a portable version of the popular website that devotes itself to getting you from Point A to Point B by train, bus, taxi, or on foot. HopStop knows the transit systems for most large East Coast cities, as well as for Atlanta, Chicago, London, and Paris. Type in your start and end points, pick a transport method, and hit Go. HopStop plots your route step-by-step and transfer-by-transfer, in both text and on maps.

FINDING YOUR WAY: Getting around unfamiliar cities can be confusing enough on foot, but adding mass transit into the mix can send you around the bend. With HopStop, just type in the addresses you’re leaving from and going to, and the app’s detailed instructions take all the worry out of changing trains or transferring buses.

STEP BY STEP: Once HopStop analyzes your travel wishes, it presents you with a list of directions on how to get there. Flick to the bottom of the screen to see the prescribed route mapped out. You can email the directions (a great feature if you’re the local trying to get visiting pals around town) and save routes that you may take again.

With 50 to 60 mini-apps bundled into one mega-app, MyCityWay’s urban guides put a city’s resources in the palm of your hand—literally. You can check local events, tours, hotels, parking lots, Wi-Fi hotspots, shops, and more. A free app is available for New York, San Francisco, London, Seattle, Chicago, Portland, and Los Angeles. Apps for Boston and Washington, DC, cost 99 cents each, and Las Vegas will run you two bucks.

OODLES OF ICONS: Open MyCityWay’s icon for your chosen city (see Chicago, that toddlin’ town, below) to bring up several screens’ worth of additional icons, all dedicated to local listings and information on particular topics, like parking or coffee shops. Tap the icon at the top of the screen to search for a business by name if you don’t know its category.

NAMES AND NUMBERS: When you find an establishment you’d like to visit, tap MyCityWay’s map icon to see just where it is. In addition to marking the spot on a map, MyCityWay lists the address and phone number. Tap the little green phone icon to leave MyCityWay and make the call. Just be mindful of roaming charges if you’re overseas.

If admiring the works of Le Corbusier, Frank Lloyd Wright, or any other major modern architect is your idea of a dream vacation, the Modern Architecture Guide is a worthy travel companion. Stocked with photos, descriptions, and facts for 3,500 buildings, parks, and other locations around the world, the app uses the iPhone’s location services to pinpoint nearby treasures.

WONDERS OF THE WORLD: The Modern Architecture guide uses your current location to find buildings of note near you. The Search function lets you look up architectural wonders by name or location. When you find something interesting, tap its listing to see the address and background on the structure. You can also get directions to it.

WHAT YOU SEE: Most of Modern Architecture Guide’s entries include photographs of the destination buildings or location so you can decide whether it’s worth your time. Some public structures or institutions have their own websites, so the app includes a button that launches Safari and takes you to these dedicated pages for additional reading.

Everyone’s seen the Liberty Bell and the Grand Canyon, but how many people have seen Delaware’s annual pumpkin-catapult contest or the “Nuns of the Battlefield” sculpture in Washington, DC? Roadside America catalogues quirky, offbeat, and just plain fun national attractions for those in search of a unique vacation. The app unlocks one of six US regions (Northeast, Midwest, and so on); an annual $6 gives you the whole country.

TOURIST TRACKS: Once you unlock your chosen region (or pony up the six bucks for the entire nation), you can browse lists of nearby attractions—or search by state and city to plan memorable trips ahead of time. Tap Roadside America’s Themes button to see sight listings grouped into catchy categories like “Dinosaurs,” “Freaky Hoo-Ha,” or “Zombie Army.”

AIN’T THAT AMERICA: On the listings screen, when an attraction piques your interest, tap its entry to get more information. The Detail screen gives you a description of the site, its address, and directions for getting there based on your current location. User-submitted photos add to the intrigue. You may find yourself suddenly reaching for the car keys.

For the sheer thrill of swooping in on any city across the globe in animated high-resolution glory, nothing beats Google Earth (on your iPhone or your desktop). Type in an address and the app “flies” you there, displaying the area using sharp satellite photos and labelling nearby points of interest. With the iPhone’s location services turned on, you can tap the Current Location button to pin your where-abouts to a map.

DOWN HERE BELOW: It’s not a new app, but Google Earth continues to improve—and impress—with its Superman view of the world and all its attractions. The app combines beautiful photographs with points-of-interest graphics. For example, tap the silverware icon above to see the name of a restaurant, or tap one of the tiny W’s to call up relevant Wikipedia articles.

HONORABLE MENTION

Google may give you the Earth, but it needs a network connection to do its thing. If you’re on a trip without access to the Internet, plan ahead with one of Offline City Maps’ 350 maps. In addition to displaying a zoomable street grid for your chosen city, you’ll find hundreds of clearly labelled points of interest and thumbnail profiles of each city, which include background info on the burg’s size, population, history, and more.

“What will the weather be like in Paris tomorrow and in Berlin the day after that?” Jumping time zones and continents can test even the most hardened road warrior, but Fizz Traveller lets you store info for several cities at once, showing you the 5-day forecast, airport conditions, local times, and more for each stop on your trip. The app also includes currency, meeting-time, and clothing-size conversion tools.

WEATHER EVERYWHERE: Once you add all the cities on your journey to Fizz Traveller, you can see what’s ahead in each location with a swipe of your finger. The buttons along the bottom of the screen show you 2-day and 5-day forecasts, the current weather conditions for each town, animated maps, and even the weather at airports in the selected cities.

MEASURED CONVERSIONS: One of Fizz Traveller’s especially helpful tools is Conversions. It not only converts currency, but measurements for weight, length, temperature, and other standards that vary around the world. And if international differences in wardrobe sizes have stopped you from buying pants and shoes in other countries, try the clothing-size converter.

Backpacking through Europe? Lingopal 44 gives you text and audio translations of common phrases (including pick-up lines) in 44 languages, from Afrikaans to Vietnamese. If you don’t need all 44 languages at once, you can buy them individually for 99 cents each. Lingopal’s free Lite apps, available for many languages (including English), offer only two categories of conversation, for the basics and flirting, but that may be all you need.

WHAT LANGUAGE, PLEASE? When you first fire up LingoPal 44, you see its entire list of available languages. Tap one to select your native tongue (which, by the way, can be any of the languages Lingopal offers) and then select the language you wish to converse in. Then pick your gender to avoid awkward moments with languages that differentiate.

TOPICS OF CONVERSATION: Tap the Categories button to see Lingopal’s range of topics and related phrases. The app covers just about all the standard traveler sayings, and a few you may not have thought of. You can add the lines you find most useful to a Favorites list so you don’t have to fumble around in Categories to utter an often-used phrase.

Need to know if making direct eye contact with someone in Japan is socially acceptable, or what gender issues might await you on that business trip to Oman? This free app offers a thumbnail view of the social practices and mores of more than 165 countries. It covers several topics, including greetings, personal space and touching, cultural taboos, and even the local drinking age.

WHEN IN ROME: While it’s not as definitive as a diplomat’s dossier on local culture and accepted public behavior, World Customs and Cultures offers a thumbnail sketch of what to expect when you travel abroad, especially in countries where the Western world is considered a bit loopy and out of touch with residents in the region.

HONORABLE MENTION

Sure to please kids who grew up looking at pictures of international flags tucked into the World Almanac, the World Factbook app does flags and much more. Compiled from information in the CIA World Fact Book, the app provides short histories of countries around the globe. In addition, you’ll find details on each nation’s current population, geographic coordinates, economy, government, communications, transportation, and military.

Don’t want to haul around a pen and roll of postage stamps on your trip? With the full version of My Vacation, you can turn your own tourist snaps into digital postcards—select a photo, tap out a quick message, and fire it off to all your pals back home to give them a peek at your journey. Both the Lite and Full versions let you record a travel journal with text, audio, and maps to help you remember the good times.

DEAR DIARY: There’s no better way to remember a vacation than to keep a travel diary while you’re still on it. My Vacation lets you save photos (for Touch users, import them), record audio and video, and write notes about each day’s activities. The app also offers local information—tap a city name to get links to maps, weather, and area attractions.

SEND A POSTCARD: Once you add photos to your vacation file, you can turn your favorite snaps into tree-friendly digital postcards. Select a photo and tap the button to send the picture as an email attachment or a Twitter update. Tap Send Postcard and your photo drops into a template where you can write a note and mail it electronically.