Using the plan tab is a great way to simulate changes to your environment without actually changing anything at all. The changes made in the plan are reflected in the desired state, or the resulting environment after the changes would have been made and the appropriate actions would have been taken. The desired state can be seen in 3 different views, which can be switched by clicking the arrows on either side of the Desired State window.
A useful feature within the plan tab is to view the VM density on the hosts in the scope of the plan. In order to do this, simply click on the Chart button in the top right of the window.
This panel will show you details for the charted data.
With this chart, it's easy to see a side-by-side comparison of before-and-after results using numbers rather than graphs. The chart gives you numerical data for host-level resources as well as the number of VMs on each host.