Here is the before.

Thank you for keeping that fabulous sink! The floor is the perfect choice!
Don’t have wallpaper suggestions at the moment, just needed to praise you for honoring that sink.

maybe do a pearlized white wall paper. you don't wanna go too busy cause the floor is busy already. your sink is your pop color, the wall needs to be simple but pretty.

like a textured white or pearly white wall paper will be subtle but still pretty

Maybe like this?

you have already too much going on: floor, baseboard, wood wall, blue sink. No wallpaper

Thanks Focal Point.

Dilaine the walls are pretty bad. Even a solid color would help I think.

You need smooth walls for wallpaper.

I don’t think pearly wallpaper goes with the wood. I would consider a narrow vertical stripe wallpaper which includes off-white, black or charcoal to reference the floor, a brown similar to the wood, and, of course, the blue/aqua to match the sink. That will take some searching. You have three distinct elements in the room which need to be balanced: tile floor, wood wall and retro sink.

the baseboard is already a focal point, I would choose the wood for the entire bath or the baseboard, and you need a super smooth wall to wallpaper it

I'd remove either the beadboard or the wood wall. Like in Highlander, "there can be only one."

But,it is your house and they do make liner paper that goes up first to smooth out a wall,then wallpaper on top.

Not a Pro.

I would take down the beadboard and paint the wood wall black. Then I would tile halfway up the wall with the same tile you used on the floor. Then paint the wall above, the same blue color as your sink.

Get blue hand towels and accessories.