Also, for 2nd body, which body goes well with 5DII? A 7D? Someone suggested the 60D? How about a 5D classic? Or even the older 40D? The thing is, I will probably only using it for those wedding sessions. On my own time, I will always pick up my 5DII.
If you're just looking for an inexpensive backup body, I'd probably go for a 40D. The main controls on the top are laid out similarly to your 5D MKII (unlike a 5D classic, where they're all different).
For me, ease of use is one of the most important to me during a wedding - the last thing I want to be doing is fumbling around the controls of a camera I'm not used to.