Hi All - taking on board your comments I have come up with three variations. Of course would love your comments! The distance from vanity to WC in plan 1 is approx 60cm - it could be made a bit more. This falls within the guideline you posted (23inches). More space could be created by making the shower a bit narrower (shown on all 3 plans as 1m wide (39 inches). I don't think there is quite enough space to divide the room and the problem with the idea of the bath right in the middle is that on a practical basis we would have to walk around it on a daily basis to get to the shower! Could quickly get very annoying!

you will have noticed that spas use natural colours, wood, stone and plants. I would nix the blue in favour of an earthy colour or a green. Consider a really dark shade suck as Dulux DH slate. I might also search the web for a new bath panel in wood, a wooden shower mat. You have an area above the bottom of the bath where you could hang a large plant from the ceiling. I might even change the loo seat for wood and get a rainfall head for the shower. Lastly every spa has to have the right lighting. I would see if I could put the light switch outside the bathroom and have a dimmer instead.

Can you sketch a simple floor plan showing bedroom, closet and bathroom, with measurements?

When I plan, i like to try to visualise exactly what will greet me when i open the door. In this case I chose not to see either the toilet or bidet, and to give the persons using those a little privacy. ( I'm guessing that plumbing requirements dictate that the soil pipe be near to the outside wall with the window on it. ) Therefore, upon opening the door, straight ahead is the double vanity with low (false ) wall behind it ( i made mine 1.2 Metres high ), This gives way to room for possibly a small shelf etc upon which to put soap etc. It also disguises behind it, the toilet and bidet, now not visible from the door. The toilet roll holder will site on the wall on the left next to the toilet. You also have room to hang towels on the wall to the left of the basins. The bath went in the top right corner ( and drains straight through the outside wall ) . Then to the immediate right upon opening the door, a large walk in shower. The towel radiator sits between the shower and the bath and is easily accessible from both. Maybe that would work for you?