In an inlaw apt we built last year, we used Hanstone's "Victorian Sands" quartz (lots of beige, black, white, some coppery tones) for the countertop with a white undermount porcelain sink & white toilet. Walls are painted in a sandy color w/white trim and looks nice. Flooring is tiled in a light cinnamon color (picks up the glaze on the vanity) with subtle gray and white streaks which relate to the white toilet. Cabinetry is a creamy beige. I used a brick red toile but could easily use a black toile in there.

I have the Subway Ceramics Avalon / Minas with a medium gray grout. And a Shaw's white sink, if anyone is considering that, by the way. (My contractor could have ordered it directly, but at his request, I went through a tile store, and by the time everyone had put their sugar onto it, it was OBSCENELY expensive.) I'm not an installation expert, but at least with the Subway Ceramics, the installers use little plastic spacers between the tiles (I think some others have their own spacers?) when they put them up, they don't do it freehand, so how much grout you get is a function of 1) the limits set by the curvature of the tile and 2) what size spacers they use. So you might be willing to go a little darker with a smaller grout line, or with a handmade tile that refuses to go close together, you might want to stay light. The traditional color is close to concrete. But most modern people don't seem to like that, so do what pleases you!

If that is the direction you are leaning, I would go with a brown-black. I don't have a particular color to suggest, though.

I can only show you pics of black iris I have. I don't think Photobucket works with houzz, but perhaps you can follow the links? Lighting affects how they look though. Diabolique-purple shows more in brighter light <a href="http://s18.photobucket.com/user/NGraham/media/iris/100_4328.jpg.html" target="_blank"><img src="http://i18.photobucket.com/albums/b108/NGraham/iris/100_4328.jpg" border="0" alt="Diabolique photo 100_4328.jpg"/></a> Here Comes the Night <a href="http://s18.photobucket.com/user/NGraham/media/iris/P1020759_zps32355bed.jpg.html" target="_blank"><img src="http://i18.photobucket.com/albums/b108/NGraham/iris/P1020759_zps32355bed.jpg" border="0" alt="Here Comes the Night photo P1020759_zps32355bed.jpg"/></a> Raven Girl <a href="http://s18.photobucket.com/user/NGraham/media/iris/P1020793_zpsc3d18487.jpg.html" target="_blank"><img src="http://i18.photobucket.com/albums/b108/NGraham/iris/P1020793_zpsc3d18487.jpg" border="0" alt="Raven Girl photo P1020793_zpsc3d18487.jpg"/></a> Send me a message if you can't view these & I'll figure it out. I have a couple of others, but I think these are very black.