Black on white is definately the way to go. I'm seriously considering it if white is an option on the R - or I might chicken out and go for Silver with black wheels. Kind of the same effect, but a little easier to keep clean!
The other question is... get the standard wheels powder coated - or buy a new set of BBS CH's in black. Obviously the 1st option is MUCH cheaper as CH's are about 2k in black 19's... but how good does powder coating actually look?
I've seen a few nice black on black - but I think its a desired taste.