Don't mix real marble with fake marble. You could use white tiles as the main field tile and accent with marble. We used a mosaic basketweave that had marble and black in a prior bath with solid white tiles on the walls and it turned out very well. What would you use for the vanity top, though? Our bathroom was so small, our ceramic sink top was a one-piece thing that was the entire vanity top so we didn't have to figure out another surface.

Here are a couple other options

Vanity will be done after bathroom. I will most likely have a gray vanity with white top.

Master shower is first. We had mold😡

These days porcelain tiles are preferred over marble and honestly look great! I did a marble look in my master bath remodel, all porcelain tiles! Used the same for shower and floor, but did matte tile on the floor. On the floor in the shower did hex which I love.