We are building new construction in a historic Victorian neighborhood. We have rather haphazardly came up with a very similar master bathroom design to these inspiration photos (thank you Houzz for having images I can see to match what is in my mind!)

We are doing the black Greek key with white hex floor tiles.

The wainscot will be a larger 4x16" subway tile, with 0.5" black flat liner with a 3.5" white Paris trim cap.

Our tub will have black exterior, polished nickel hardware/feet. Height 22.5" to rim of tub, faucet comes up 13" to a total of 35.5".

Originally our designer recommended going no shorter than 48". We are finalizing our tile plans and in my review decided to search out visually how these heights might look and I came across these images. Looks like the height is ~42.5" (6" base, 11 rows of 3", .5" black, 3" cap). I like the height considering it will wrap the room. Having hard time imagining it at 48" now.

We will have 10' ceilings so maybe 48" would look better? Likely will be a wallpaper above.

Would 42" or 48" look the best for the tile wainscot?

We have a natural break with the shower and vanity cabinet so I was not planning on running the flat black liner into the shower.

Classic Subway Tile Bathtub Surround · More Info

Subway Tile Shower · More Info

Subway Tile Shower · More Info