What is your vanity style and color? Your house seems pretty transitional so almost anything goes. You could play it safe with either square or rectangle white subway tiles they are easy to work with and easy on budget. You could use the floor tiles in the tub area as well. There are also many faux marble porcelain tiles that are nice these days too. Not as pretty as the real thing but no maintance. I used faux marble in my shower next to silver floors, mahagony vanity and no tiles on walls just a blue washable paint for a cool bath with touches of warmth.

I think that is your vanity in your kitchen, isn't it. Sorry I did not catch that earlier. I would not use faux marble near the real thing. Can you post your floor tile.

How about a mother of pearl look

You will need proper waterproofing before you do anything else BTW.I like the floor tile for shower walls it keeps things simple in a small space , you could add an accent tile but that floor is very industrial looking so you will have to be careful with what you choose.