Walk in shower - getting rid of a door means you don’t need any of those rubber seals that yellow and collect gunk.
Two sinks so DH and I aren’t dancing round each other as we clean teeth. Only if space allows of course
Dual fuel towel rail and underfloor heating (maybe slightly overkill!)
Two sets of lighting - one brighter/overhead and one more subtle. Put at least one of these on a dimmer.
Decent (quiet) extractor fan, wired to go on with one set of lights.
Large tiles to reduce grout lines. Non white grout so it doesn’t show every bit of dirt.
Vanity with deep drawer (shallow drawers are useless for toiletries)
Not a rainfall shower, unless you have amazing pressure
Separate hand held shower for rinsing hair and cleaning shower
Shower controls on separate wall from shower to avoid wet arm
Niche
You can also recess a shallow storage cabinet into any untiled stud wall - deep enough for bottles
Wall hung loo and sink/vanity makes room more spacious, and easier to clean
Compact loo - Villeroy & Boch Subway 2.0 compact looks and feels like a normal loo but has a very short projection, good for space saving. Rimless loos are good. Avoid loos with a poo catching shelf (many european brand loos have this)