I told my tile guy I wanted to be able to use chemicals in the shower so I used ceramic tile (instead of natural stone) and he used epoxy grout. It's been a dream to keep clean so far. I get that pinkish mold...spray it with some clorox and water, let it sit for a couple minutes and rinse..good as new.

that's very similar to the tile we used in a bathroom. We did go with white grout -- here are a couple of pics so that you can at least visualize it with white. I bought some kind of special grout that i had read about on the bath forum for mosaic tile. It was several months (and a whole kitchen!) ago, so the type/name escapes me, but I will look at home or ask DH and post again if i can remember it.

You paid for Walker Zanger tile in the first place. Is there any way you can send them the tile and have them lay it out again and paper the front for you? After all, the paint has been removed and the tile is intact. I understand that you're keeping the same installers in part because they are picking up the tab for replacement tile, but if you can salvage the WZ at this point, maybe you should have someone else install it. Cheating indeed. Jeesh.

Ok, so not in shower. Even so, make sure it is a wet-rated tile so you have no regrets. I would get all your components together first (main floor, shower floor, shower walls, wall paint color) before selecting your grout. All of these things will make a difference in which color grout would work best....because you may end up with a floor that calls for a grout color that fights against any grout color you choose now (ie similar grays that clash) or your wall color may pose the same issue. Try to collect those other materials (door sample, countertop sample, backsplash, floor sample, shower wall sample, etc) and put them all in the actual space they will live and then look at grout :)