I'm one of the captains for the performance module of the Hands on Labs at VMworld this year. This means that I got to really geek out and create a new module that focuses on using esxtop. For really in depth performance analysis on ESXi - esxtop is my favorite. Come by the Hands On Labs in Moscone South this week take SDC-1304 Optimizing for Performance. All of the modules are great - but my new esxtop module is number six. Skip straight to it by using the table of contents once the lab has started.
The labs are currently only available onsite at VMworld, but will be made available through the public Hands on Labs portal at some point after the conference ends. So if you couldn't make it to VMworld this year - don't despair, you will be able to get to the new labs in the future.