I use the Planing Tool and disable all provisioning posibilities (this to see what's happen with the current environment).
Sometime I get VM they could not be placed on any host.
My Idea is to put more information into the report to understand why the VM is un-placed.
(like: "not enough Memory to start the VM because of HA Setting restrictions" or "not enough Memory and CPU available")
Such information is usefull to decide "do we need new blades" or "do we need only a RAM upgrade on the blades".
Additional to this the info about the current HA Settings could be usefull in the report. If a Have a Cluster on wich are the HA Settings 50% for CPU and RAM, my manager can see this fact in the report. He see there is only 49% RAM in use and don't understand why we could not deploy the additional VM's. Maybe a line (HA Restrictions) in the Graphics can help.