How can we monitor the environment? You can use two ways: the first from a OS VM perspective and the second from a third-party tools perspective. 

We can use two views to monitor the environment:

• Inside the Guest OS tools: Task Manager or top
• Outside the Guest OS tools: vCenter Server performance charts or esxtop

As per my point of view and experience, CLI is better and more helpful than GUI tools. However, of course, you can find any GUI that you love.