I am surprised to see the lack of love for the silver. I wonder if gold seems to be a popular choice because it is new. It's pretty, sure, but I would be tired of it very quickly.
The space gray looks sort of nice, but it just reminds me of a Dell/Sony and the fingerprints would drive me nuts. The only reason I have a SG phone is because of the black bezel. I would get the silver phone if I could get the black bezel too. To each, their own, I guess. Glad Apple offers the option now!
I think you hit it right on the money you think just like I do. Gold and Space Gray are the "new" colors and will get much more attention than plain old silver because its something different for Macs.