I'm interested to hear some examples of how people manage capacity planning - basically, what signals do you use to tell you that it is time to buy some more servers and add them to the cluster?
Do you use a capacity planning tool, and do what it says? A custom script? The users telling you it's running slow 
?
The vSphere Monitoring and Performance guide does offer some very basic guidance - has anyone used this guidance and the suggested figures? How well does it work?
Can anyone suggest other documents that offer useful info?
Thanks in advance.
Cheers
Tim