Maybe some wall mounted sconces on either side? Above the mirror lighting doesn't seem like it will be feasible so that may be your best bet.

We have a 45 inch vanity that comes with a standard 48 x 42 size mirror. So your mirror is wider than your vanity? Consider turning your mirror vertically for a special look.

To answer questions, I was able to add more pictures. Here is where the chandelier will hang. It is centered in the room. This is looking into the bath from center entry between closets on left and right. The room is roughly 20ft left to right, with shower and my vanity at opposite ends, and 12 ft from the entry to the back wall alcove where the tub will sit. The blue tape is stuck to the mount where the light will hang, and is 36" long just to see proportions. My husband standing under it is still a few feet from his head (he is 6'3"). Ceilings are all sots of height as you can tell but roughly 10-12' max. The chandelier above is L29w29xH32.5. Or they have a smaller one 25x25x28. Which size?? Oh and I don't have pic of the vanity as they are covered. But the suggested pics above of dark vanities is spot on color. My larger vanity is to the right here buried under the ladder etc.! Thanks for feedback!! LM

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/