I use an IBM Model M, so I don't actually have Win keys. In Windows, I've had right-alt set to act as the Win key, and I'd like to set that up on Ubuntu as well. I went to the Keyboard Layout Options 
and found an option for Left Alt is swapped with Left Win, but I didn't see one to do the same for the right.
Swapping the left just doesn't work for me--Alt+Tab is particularly difficult with only Right Alt acting as Alt. Am I just missing something, or is there no way to swap Right Alt and Right Win?