If this is for the bathroom floor, not the shower, you may be fine with white grout if it is sealed. Do you drip hair dye? Is this a bathroom used by males who do not aim well? Will people have anything else in there that can spill and stain? If not, the white tile floor is pretty popular. People may use a more off-white grout, though. Wait and see who shows up to comment.

Yes, the grout will need to be regularly sealed to stay white. My big drawback to a white floor, though, is the fact that the floor is white! Every stand of hair, speck of dirt, dribble of ... anything ... will show up as if illuminated. Would this drive you crazy? Yeah, yeah, I know that stuff is on the floor whether I can see it or not, but I'd prefer it not be quiiiiiittteee so obvious! :)

I have marble basket weave tile which has a lot of grout. I used a light gray and not a white for the grout. This was what looked good and also was intended to minimize maintenance issues. It has been over two years and it still looks great - there might be a few places where something small drop is causing minor discoloration but it just blends.

My floor is not pristine white though - it is Calacatta marble. However my experience with white tile is that it is pretty forgiving - black and dark tile however shows every bit of dust just as is true for dark wood floors as opposed to lighter floors.