B.F.
There are a lot of good ideas here. Gray needs a LOT of light not to be depressing. When out lining something don't use perminate marker, that what won't come off, use a paint pen. You could use a large vinyl wall decall in white or green on the gray. Before you do anything, look at the powder room on the HGTV Dream House. They have photos you can look through, gray walls with green pinstripe horizontally. I would come close to doing one wall like that depending on the design of the bedding. Good luck!