We painted our "kid" bathroom room with a fish/duck theme. I had their towels monogramed with their names on the towel rod behind the toilet. I bought removable bathroom friendly stickers that are made for bathrooms (in my local craft store), they are ducks and stuck them to the tub, glass mirror, handle to the toilet, and even the light switches. Target had a neat bathroom set of duck towels that I complimented their other towels with. So the color accents were a darker blue (for our boy) and yellow (for our girl). We also have a fish shower curtain. Hope that helps. Good luck decorating. Another thing is after your kid(s) get older you can remove the stickers, the ducky theme feel and still keep the blue and doll it'll up more adult like.
A. B