There is a lot of movement on the walls and I think marble on vanity tops may be too much. I think your original idea of going with something simple and white is much better. Also, quartz is much easier for maintaining and caring for than marble. So, perhaps something like Blizzard quartz from Caesarstone https://homearttile.com/product/2141-blizzard/ . For vanity, I would go with something darker to create contrast with the top and walls, something like https://homearttile.com/product/eviva-aberdeen-72%e2%80%b3-transitional-espresso/ or https://homearttile.com/product/eviva-natalie-f-60%e2%80%b3-espresso/ or smaller https://homearttile.com/product/017-24-02/

I think your walls have just enough marble -- the look is stunning. But I wouldn't go with marble on your vanity tops, except if you find marble that is very light/white with pale veining, something that wouldn't compete with the walls. Also, I would go with a light or white vanity to contrast the walls and large mirrors to open up space.

The only way that I would choose marble for your tub deck and vanity would be if you matched the marble tile 100%, and did a wall hung console in it, creating a color block look that was punctuated only by the white of the fixtures. That would be a pretty severe and cool look though, and difficult to pull off without some greenery for life and very good lighting.

Otherwise, stick with either a gray that matches the veining, or a white. But, with added wood touches.

I agree either perfect matched marble or go quartz in plain white the same color as the white in your marble BTW Also that wood cabinets in your pic is all wrong with marble and IMO so are the black faucets

Thank you all. The marble I am considering for the vanity is all white, hardly any veining. The vanity itself is going to be white oak and we were planning to do a light stain. Our plumbing fixtures are polished nickel.