I'm not sure of a way to limit the view of the guests running when you drill down into an ESXi server. However, host details are available via the guest views. For instance: if I go to one of our VMs I can see all of the info about the host that it's running on (except for other VM's). This also shows the impact of the selected VM on its host and host details including network, CPU, memory, and then you can even throw in disk performance using something like SNMP Informant.
Okay, I've seen that page, problem is I don't want the customers to be able to see what the total CPU usage, memory etc on the host is. Only what effect their servers are having on the host.
At the moment I've created a custom Group Summary view that has all their servers in it and although it's not giving exactly what I've been asked to provide it's giving something without compromising information on our back end infrastructure... Just waiting for our salesman to let me know if that's good enough!
If anyone else can think of anything please let me know!