Lovely tiles! I like that they cover the back wall. The sink looks great too! Here are some guidelines to think about for a wallpaper: Your tiles are a small scale. So pick a wallpaper that has a medium or large pattern to contrast with the tiles. I would stay away from geometrics, again for contrast. Something with a flowing, natural feel would work well - think florals, branches, or grasses. If your bathroom is headed in a more modern direction, something with abstract swirls possibly. In order to let the tiles stand out, use a wallpaper that’s tonal - as in subtle color variation and very low contrast. You have a lot of leeway in what color you select. Personally, I would use something in varying neutral shades, like cream to taupe. But you could us a paper with a subtle pattern in shades of greens, blues, or reds. Maybe dark grays or near black if you want to get dramatic. Hope that helps! Best of luck.

Beautiful art. I don’t know what styles you like, but since the rest of your rooms are white, I’d go with more drama and interest in the powder room. Wallpaper all of it, paint it a dark color, or just do the sink area. Again, not knowing your decor aesthetic, just posting these for general ideas. I think a retro glam style would look sophisticated and gorgeous, and highlight and compliment your art. ETA: This has such pretty colors — wallpaper accent wall with paint. Bold and dramatic doesn’t take away from the art at all ....

I have wallpaper in both my master and guest baths. There is only one section in which the wallpaper meets the counter and so I decided to have a remnant from my marble counter installed just in that section. I realized that there would probably be some amount of moisture meeting the wall just from having someone potentially clean the counters. It is just the standard six inch type of splash guard that is typically installed when there is no full backsplash. The wallpaper is just to the left of my sink ajd I am not worried about splashing the wallpaper but what wouid happen over time as the bottom of the wallpaper continually came into contact with moisture and cleansers. Clarifying that I have ceiling to counter mirrors in front of the vanity so the wallpaper is only in a small section to the left of the vanity. Prior to my remodel I had one of the six inch splash guards extending the length of the double vanity. Perhaps I wasn't the most meticulous housekeeper but it would accumulate gunk and periodically would be resealed with caulking. I would imagine over the long term that would happen if wallpaper met the counter and there would be no effective way of keeping it de-gunked. Having one of those six inch splash guards is done pretty regularly in kitchens and bathrooms when there is no backsplash.

I'm also loving the moody blues but I agree with @jck910 in that the paint should blend with the floor. I was going to suggest SW white egret but I just watched a video on it and the video said if your room doesn't get a lot of light it will make the room feel dingy. I used it in a room with two sky lights so it wasn't. That said, I think something warm and white/creamy would be good just from looking at our picture. I would freshen up the trim and window sill with SW extra white in semi gloss. So many colors to choose from!