I think that would look great with floorboards in a classic walnut colour, that would definitely look great with the light cabinets. If you want an idea of how it might look with the end finishes, you can type this into google and they should be able to show you a few.

That timber top on the vanity would be tricky to makeover unless you had a piece of composite stone cut for it, or even a squared off laminate counter. It all depends how much freedom/budget you have. Can you see a time in the future that you are likely to update the bathroom completely? For now, it might be simplest to just paint the walls above the tiles Antique White USA and purchase a black bakelite toilet seat/lid. Replace the cabinet knobs with some shiny black round ones and the room will take on more of a classic 1920s feel as opposed to Victorian meets 1990 one.

Have you priced having the whole lot re waterproofed and tiled? You are already doing the hardest section, it may not be that much more to do the lot. Otherwise agree with above match to the white tiles in the rest of the bathroom. But it will always look like a repair.

This is a very personal choice as dreamer mentioned. You can order tile samples from tile cloud or TileMall for $15 for 5. Pick some options you like and put up in the kitchen next to the other elements. You will soon know which one you love the most 👍🏻