Seriously you need to check out the Kerlite cladding. No need to sand, the variety is huge even wood look. All you need to do is put on a thicker screed. As I said you do need a tiler that has laid it before. Once it's down, it will never break. Google it, the range is amazing and really beautiful. I did ask the tiler about using it over slate and he said not a problem. Got mine from tile expo.

According to the converts they are the wonder machines that do absolutely everything!! They chop, blend, cook and have a steamer thingy which goes on top, but I'm sure Sharon can explain better, it will be good practice for her giving her husband the sales pitch!

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.

Congrats