If you really want your all white decor to pop, then add a colorful abstract canvas painting like this one on canvas from the Etsy shop, ArtFactory. It features pretty much every color imaginable from blue to red to green to orange to yellow with pops of black. Obviously it looks really great in an all white room, but would add a much needed burst of color to a plain powder room. It is a bold graphic print that has a Picasso like feel to it, ideal for your modern or contemporary decor.
You might also like this Blue Abstract Art Print.