I don't really like the beige color of original m's that much, to tell you the truth. They're nice looking in the right looking set up, and are nice for authenticity's sake, but on my desk they just look ugly.
I think for the 122 key, you probably want to go with either a dark, dark blue or a black. It's a giant keyboard, so it'll take up a giant chunk of your desk. Therefore it's probably best to have a color that'll go with anything. It's fine to have a small keyboard like a poker in a cooky color like pink, just because it'll end up looking like just a small detail on your desk. Can't really do that with a 122 key model m,
But, for the highest resale value, I think it'll be best to just keep it in it's normal color