Bathroom tiles floor-to-ceiling or half-height tiles?

Yes, the guest WC door opens outward

hmm in your solution, however, there are "ugly" tile edges because the tiling does not stop in a corner but in the middle of the room

our current options

1. Tiling up to the ceiling
2. No tiles on the door side and/or the opposite wall (only baseboards)
3. Accept the gap in the door

For the floor plan, I would choose your 2nd one.

then probably both sides will skip the tiles, right? just not tiling the door side would probably look weird, wouldn’t it?

our tile colors:

floor tiles: wood-look
base shelf = floor tiles
wall tiles: white with a slight texture

What is the base shelf? The baseboards? Or the top of the pre-wall installation? Oh, and yes, then only tile the wall with the washbasin and toilet, not the others.

Yes, sorry, I obviously mean the installation of the pre-wall system behind the sink and behind the toilet at 1.20m

So again, you would tile the wall or the pre-wall installation high (behind the sink and toilet) and not tile the door wall and the opposite wall?

To summarize briefly, tile the short walls up to 1.20m and not tile the long walls at all?

Yes sorry, I mean of course the installation of the pre-wall behind the sink and behind the toilet at 1.20m

I would rather tile that with the wall tile.

So once again you would tile the wall or the pre-wall installation up high (behind the sink and toilet) and not tile the door wall and opposite?

Yes.

Quick summary again: tile the short walls up to 1.20m and not tile the long walls at all?

Yes.