amusing story related to this...

I was in the plane and sitting in coach w/ some other colleagues (all elites) and the FA was going down the list to bump some of us up to first, as seats were available still. A few of us declined, as we were fine in coach and didn't want to move our bags, but another colleague said she'd take it if offered. I asked the FA is she could have the seat in first that was offered to me, and before he could respond, another passenger yelled... UPGRADES ARE NOT TRANSFERABLE!

eeeekk... lesson learned, don't mess w/ anyone's potential upgrade!