I don't know about a black sink. It's almost like a black car. Did anyone ever notice that if you have a white car, you don't need to wash it as often as a black car. Black shows everything. I think you would have to be Mrs. Clean to have that look good all the time.
Glad you are going with the darker color, like I said in my morning codie post, I rethought that one. There wouldn't have been enough contrast to draw you eye to the subway tile.
What type of material for the white sink? Porcelain, or they also have like a soapstone or whatever. I had one of those, the soapstone. They are very porous and easily stained. Go with porcelain, but just a suggestion.
Also, don't just disregard stainless, I was going to do that. I got a brushed stainless, and I liked that one. It was that mirror like effect, it was easy to clean, and also check out the gauges on those.