Using the cavity for mirrored shaving cabinet above vanity would give a lot of storage and remove any clutter. I wonder about recessed towel racks in current position next to shower though, I think you'd be better off getting rid of those rails and putting in a double sink vanity which would butt up to shower with another recessed, mirrored shaving cabinet above for more storage. You'd get more storage for larger items like towels in a cupboard type vanity. Style is personal, I'd introduce some timber to warm up the room but that's me. Have vanity mounted to create a more spacious look exposing more of the floor.

There's another towel rail showing on the opposite wall where you could add a heated towel rail system, recessed if you like. If not heated and recessed I don't think your towels will dry between showers, depending on where you live of course.

Another area for recessed storage is above the toilet and on the wall above toilet roll holder. You won't get much depth anyway with recessed option so what do you hope to store in all these spots? I'd go for a timber shelf above the loo, even if it's only to hold a colourful piece of art or a picture.

It's a small area, remember changing plumbing is expensive if you're wanting to change the whole layout as well. You could put in a bath with shower over if you want one although it looks like it works as is to me, perhaps you just need to add a bit of colour and change the décor to make it your own.

I like the high tile line and the colours are neutral and l've always liked mosaic tiles in the shower although I'd have taken them to the shower floor myself. I'd prefer your ensuite as is to mine any day btw, I could trick it up without spending more than a few dollars.

Having had a very similar laid out ensuite in the past, I'm doubtful there are any other layout options, as you'd need more width in the room. It will depend what is behind your shaving cabinet for it to be recessed. We had double brick with plumbing chased in!

I can see how you'd get a longer vanity in, allowing for more bench space. You'd need to do away with the towel racks completely. You can always put your towels in your bedroom? We used to do this and found they dried better out there anyway.

https://www.bunnings.com.au/our-range/bathroom-plumbing/bathroom/decor/towel-stands

my suggestion include rotating the toilet and/or using a concealed toilet cistern to save knee and wall space to allow for a 1500 wide vanity, in wall mirrored wall cabinet up to 2.4 m wide, relocating the internal sliding door allows more central standing room and privacy when the door is open, recessed shelves inside the shower and stacked and/or heated towel rails near the toilet (btw although we're very happy with our concealed cistern toilets they are much more expensive than average toilets and a careful search for the smallest toilet is worthwhile

have you looked at a sliding shower door for space saving. We had Opto Inline doors installed in both our bathrooms, easy to clean and they look fantastic. No door to get in the way and came in under budget.

i also prefer sliding glass doors but this bathroom is only 1100mm deep and would need triple panel sliding glass doors to be able to retract next to the end of the vanity which could be a problem allowing moisture through to the vanity and a two panel sliding door having an opening of 550mm or an asymmetrical 450 panel and a door 650 the opening may not be wide enough for comfortable use but a screen specialist will clarify most suitable option

WOW they didn't waterproof, what a shock, I'm surprised their renovation was signed off by the builder, unless it was a diy job. It makes the house unsuitable for habitation doesn't it? Just saying I actually don't know the rules.