We had our bathroom and ensuite done earlier this year. Second getting wall hung toilet and vanity unit and arranging so you get totally hidden pipes.
We have a deep one drawer vanity in the bathroom and a 2 drawer in the en-suite, two drawer is much better for toiletries (we keep cleaning stuff outside bathroom). We found moving the toilet position to another wall was a lot easier than we thought and the price difference in the whole job negligible. I would avoid any plumber that isn't keen to move the soil pipe or can't give you hidden (not boxed in) pipes (unless really awkward). We had plumbers saying it wasn't possible and everything needs to stay where it was. Then this guy came along and just said yep I'll move the soil pipe and I can put your sink pipes in your wall cavity, and move your towel rail along the wall, no problem. His quote was actually cheaper than the others.
If you don't know a plumber or have a personal recommendation ask tile showrooms/bathroom showrooms for recommendations. Be prepared to wait months for someone to fit you in their schedule, good plumbers are busy.
If you have the shower over the bath there are also keyhole baths which give you more flexibility with what you can do with bath sides (we wanted to tile ours). We got one that was slightly wider than standard and it is great for a good long soak.
Replacing a radiator with a towel rails is great, make sure they have enough (and not too much!) BTU to heat the room.
Shaver socket in mirror for charging toothbrushes and shavers.
Visit showrooms that have wetwall full rooms in display or friends with bathrooms done. We really liked the practicality idea of boards and got loads of samples in, but good looking ones which are usually acrylic rather than plastic expensive, and they do have a certain caravan look. We did go for the ceiling panels with spots which we were unsure of with tiles, but look good fitted.
If you go for tiles, coloured grout makes a huge difference to the look of the room.
Flooring is another huge consideration, I don't like hard cold tile floors so we went for vinyl click flooring and not keen on it down/walking on it.