Love all the wonderful comments above. The only thing I would add is: really consider what you want to use this room for... What do you want the room to do? Welcoming guests? If it is welcoming, then think about what makes you feel welcomed when you walk in - that ahhhh feeling.....maybe plants (a bonsai project would work well in that light), some family photos instead of a mirror, coat hanger behind door, buffet table (where you stand your G&T chrystal set on a nice sliver tray). Or is it a Staging ground for getting out the door? Then perhaps the mirror, some sort of rack for bags & hats etc, a bench for sitting and putting on shoes, cork board for reminders etc (it is possible to have these all behind a thin closet so closed doors hide any clutter). Whatever you choose, I just find it helpful to keep the rooms purpose in mind.

Is your final photo of the vanity you already have? I also thought adding legs would take it back to the MCM you are after. Would be interesting to know how the silver drawer pull is attached. Not sure about painting it matte black as I thought timber furnishings were more prevalent then, but it's totally your choice. I hope you will post updates as you go. I just love mid-century.

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.

Thank you everyone, lots of food for thought. oklouise, would you have the false wall going all the way along the bathroom or just jutting out behind the vanity? We have a few cm to work with as the vanity we are looking at is a little narrower than it could be. jacqueline thank you so much for your photo! Something that goes down a bit lower might help disguise the pipes, ours will be a much smaller room than yours. siriskey, I have attached the plan for this room to see if it is helpful. I am leaning towards choosing a different vanity but as you have said this one is lovely! But it won't be lovely if it doesn't work...!