At work we're running 3 instances of vSphere/vCenter 4.1 Essentials plus. We have 9 ESX boxes. With Essentials, you can only manage 3 hosts per vCenter. For vMotion purposes, we've recently grouped the servers by compatible processor types:
vCenter1:
ESX4,5,6
vCenter2:
ESX7,8,9
vCenter3:
ESX1,2,3
Yes, we are legitimate with licensing but kept adding boxes over the years. The challenge is arranging the vCenter VM's appropriately. Currently vCenter 1 and 2 run on ESX9, and vCenter 3 runs on ESX7. We have two sites connected via 50mb ethernet.
Our goal is to re-arrange the physical servers so we have six boxes at one site and 3 at the other (vCenter 1 and 2 at site A, vCenter 3 at site

. But which hosts should run which vCenters, keeping the WAN factor in mind? Hope this makes sense...