Hi,
I've been tasked with commencing the complete replacement of our current ESXi 5.0 U2 hardware environment with a new cluster of servers running 5.1.
Here are the basics:
Currently HP Blade Server Chassis with 6 hypervisors running ESXi 5.0 U2, Enterprise license, around 100 or so VMs running various OS's - mainly MS 2003 R2 and 2008 R2, data stores on SANs connected via 1GB ethernet connections.
Planning to run 7 independent servers as a cluster with ESXi 5.1, Enterprise License, connections to SAN to be improved to 10GB ethernet or fibre. The VMs range in importance from "can be rebooted after hours" to "must not be restarted or it will cost us money in downtime". (Looking for any options to live-migrate where possible although I have my doubts this will be an option given the inter-cluster plans)
I'm looking for a Best Practices Guide (or combination of guides) that will help me determine the best way to plan for the VM migration - especially in light of the fact that the new cluster will not be part of the existing one. Also in light of the fact we cannot (due to firmware issues on the blade chassis) upgrade to 5.1 prior to this work...
Any pointers in the right direction would be great - not looking for a handout, just the signposts people 
Cheers.