The choice is yours. Whatever one you do dark will make that being the floor or walls look like a smaller space. I think that the grey and white looks great...mm perhaps I would the lighter tile on the wall...so it won't close it in. Unless you can the same time for floor and wall if it is a floor tile you can if not you can't. have lots of mirror as well... this will open up the room and tile floor to ceiling. Make sure that your tiler is licensed for waterproofing as well as tiling...ask them for a proof of insurance which is a certificate of currency and that they produce their tiling license.....or don't employ them...all the best. Robyn