We're in the middle of P2V'ing most of the network, so the current backup method is likely the worst - the backup agent is still installed on the guest OSs, and the backup device is dutifully pulling them onto tape, one file at a time.
I suspect there's a clever way to script (PowerShell?) a suspend on the VMs, then backup of the .vhd files, and unsuspend the VMs. This seems like it would provide big speed benefits, while losing file-level restore (might be best for things like DCs and app servers).
What methods/policies have you hammered out?