A walk in shower and a separate bath if you have the space. Shower to have a hand held option too.
Aqua wall panels throughout, instead of tiles (no grout, etc).
Large basin with ledge for putting soaps, stuff whilst you're doing makeup, etc.
Under basin unit with drawers (we're going for an 800mm wide basin with two drawer under unit) to hide all your shite goodies.
Large, mirrored and lit bathroom cabinet.
If you don't have radiators, then a heated towel rail to dry towels.
Decent extractor fan.
Good lighting, zoned if you can, especially over the shower/basin.
Hand held shower head taps on the bath for hair/bath washing.
Double ended bath.
If you have tiled floors, avoid white grout.
Make sure the loo roll holder is near enough to the loo that you don't have to be a bloody contortionist to reach it.
Ditto hand towel rail near the basin to avoid drips.
Soft close loo seat (for eejits that can't close a toilet seat quietly I'm looking at you current house guest)