It really depends on the other items in the scheme and their tones. Lighter tiles - especially on the floor - make the room brighter while allowing darker walls to add depth and contrast. The darker walls also make the white of the sanitaryware stand out. Try Farrow & Ball Purbeck Stone or Worsted in a modern emulsion for grey tones or Little Greene French Grey 113 or Lead Colour 117 for a warmer effect - both offer a neutral backdrop. If you want to add a pop of colour try Farrow & Ball Green Blue or Little Greene Marine Blue for duck egg/teal colours that are right on trend.