I would do a pedestal sink, or a funky vessel sink. I'm stumped on the vanity finish.

Houzz.com has thousands of pictures of black and white bathrooms-
might give you some ideas.

I checked Houzz.com and most of the b/w bathrooms had more white then black as I do. Only saw a few with black tubs and those had mostly white tiles.

maybe swap out cabinets for natural maple, rather than white.

I can see your bathroom with a white pedestal sink (as mentioned above) and a wallpaper or stencil like this bathroom has. And hang a shower curtain,white with green trim like the shade.

I can imagine the ceiling in this pic being your tub/shower and the colored walls really bring it to life.

[Contemporary Powder Room design[(https://www.houzz.com/photos/contemporary-powder-room-ideas-phbr1-bp~t_713~s_2103) by Philadelphia Architect Priscilla Fenlin Interiors

I'd put a white console sink in.
It's a pretty bathroom.