I have installed pebble tiles in several showersPros - very elegant, gives a sense of space as pebbles are different so no long defining linesCons - difficult to clean, must determine at outset if you want the stones deep in grout (you see lots more grout but the surface is smoother) or not so deep (you see less grout, but the surface is bumpier).Some people recommend epoxy grout, I don't for the simple reason it is much harder to get the grouting even with pebbles than tiles so more time needs to be taken.

Out of your selection - I would choose the middle one on the bottom row - it gives you a modern look and pattern without being too ghastly - it would fit in with the retro vibe as well. Good luck!

I love those long floorboards/wood-look tiles and they are the feature so you wouldn't want something too busy on the walls... personally I would go with a larger format say 300x600 rectified edge white tile with a matt finish for the Hamptons look... what's your vanity?... a timber one would tie in nicely with the floors and all the white... very Hamptons :)

Sounds like a very stressful situation! If there is absolutely no way the builder will allow you to change things (even if they did, I imagine they would ask you to foot the entire bill of pulling the tiles down and replacing all water proofing in addition to new tiles), I can make a few suggestions for improvement. Firstly I would suggest replacing the tiles above the vanity with a white mosaic, a patterned or a textured feature tile/strip. You could also use this same tile to replace the vertical feature in the shower. There are some beautiful shapes and sizes available to choose from. Secondly I would address the grout situation in this way: Floor - dark colour grout & Walls - Light colour grout. Lastly if it does not prove too difficult or expensive, maybe replace the tiles below the vanity with a plain white tile (could be similar size). Good luck and I am sure once you have a lovely mirror up and some crisp white towels, it will look just wonderful.