Artwork.....something bright for some color and punch....yellows and reds look great with gray.

I would pick a single 3rd color to contrast with the black and white and add it to towels, bath mat, window treatment and art work, accessories. As you have a neutral palette, you can pick your favorite color...or have your kids vote on it. Green, red, aqua, turquoise, tan, gold, yellow, any of them and most shades of them...

But be sure to add the color with balance...you don't want it everywhere or lopsided in the room. So add it thoughtfully.

I am stuck on only using white towels and bath rugs. For decor, I'd put a fake orchid in there. A crackled glass translucent jar with a pretty lid to keep soaps in. There are all kinds of fun appliqués and decals you can put on the wall. Fun and pretty postcards framed in inexpensive plexi framesâ¦

Decals:

Thanks for the replies. Can anyone send me a link of some artwork you think would work in my bathroom? Also, what other forms of decor are there. I keep thinking maybe a wreath or some fake plants/flowers?

I have a white, gray and black bathroom used by teenagers and guests. I hung some penguin photos that I took in the Falkland Islands. I think they look good. :) I'll put up some pics if you want to see them in the bathroom.

I'd stay away from the wreath or fake flowers if you can. (Though I admit to having fake or dried flowers in mine...they are detested by many.) Instead there are other attractive bath accessories you can get from towel holders, tissue holders, soap dispensers, and things to hold cotton balls and q tips. But I wouldn't go too crazy with kids using the bath primarily...

As far as art work, you don't want anything expensive as the moisture in the room could damage it, so stick to prints and such or you can hang things on the wall that are less affected by moisture like plates.

Perhaps you should go to houzz.com and look at the bathrooms there for some ideas.