Remove all items from the bathroom to see its fundamental structure. Notice if the room is too narrow. Consider opening it up with a light color on the walls.
Tear up old tile and install a dark slate floor tile to enhance the gray of the fixtures and add a more upscale, modern look.
Repaint a low ceiling with a white, light-reflecting paint to create more bounces of light to counteract the dull gray.
Paint walls white and add black towels, rugs and accents to provide graduation of tone to the gray toilet.
Add a graphic printed shower curtain that contains small amounts of gray in the pattern.
Add a white wicker hamper, shelf or table to add natural materials and warmth to the room.
Add silver or chrome accent pieces such as picture frames, soap dishes and other toiletry articles to repeat the gray color while adding light reflection to the room.