Teal paint or wallpaper does work, it all depends on the feel you want.

Are you looking for Whimsical/cottage? farm house? or Glamour? Drama?

I did our powder room in a very dark teal blue wallpaper. I put a large mirror wall to wall across the sink and almost up to the ceiling (7 ft), then mounted the sconces on the mirror for maximum reflectivity. They sparkle. Its a small room, only 40" across. The vanity just fit. It's white with a white top. The flooring is hardwood, medium color.

So far, every single person who has seen the room has complimented it. :)

Love the cheery bird wallpaper. I would match the teal in the bird to your paint. Nothing muddy looking, get a brighter clearer cleaner looking teal.

I once chose a paint color for my family, living room and kitchen from one small area on an abstract painting of a horse that our friend painted for us. I loved the color. I just found the SW chip that matched. Look at your lovely bird wallpaper and choose your favorite hue.

The teal would look great. I had a bathroom with no natural light and used a fairly dark color in it but used one that was a bit cleaner like you're planning. It made the room

I really like that lovely wallpaper! I think teal would be just fine in that space as long as you have proper lighting. As an alternative, if it were my space, I would match the white background of the wallpaper for the other walls in order to make the pattern of the wallpaper be the star of the show. But I think the teal would work well and look lovely in the space too.

An oval mirror would be very nice. I'm a huge fan of wall mount swivel mirrors because they really add a special something to the space. I think putting them over wall paper would also help the wallpaper show even more because you'd see it peeking behind the mirror.

Pottery Barn Kensington Pivot Mirror