Single-family house with main bathroom on the upper floor: bathroom planning experiences?

It should be interesting when you furnish the floor. Staircase 1m wide, hallway 1.25m wide. No maneuvering space. Have fun with a bed, children's sofa, desk, wardrobe.

we find this a bit cramped.

Me too. Who would want the shapeless impractical shower?

unobstructed view of fields.

The panoramic window should be a bit bigger there. Personally, I am not a fan of watching the rush from the tub. I bathe when it is already dark outside. In summer or during the day, that is inappropriate. I think you should consider that. For getting up at night, however, I always find a few seconds to enjoy our panorama of the cathedral.

It could get interesting when you furnish the floor. Staircase 1m wide, hallway 1.25m wide. No maneuvering space. Have fun with a bed, kids’ sofa, desk, wardrobe.

Make sure to allow the side space for the handrail plus 100cm around the stairwell. Otherwise, later you may not even be able to carry the kids to bed or bring up furniture packages / laundry baskets.

I would make the stair landing one step narrower, then you save one step width on the upper floor. Then you could move the bathroom door about 25 cm towards the top of the plan and place the washbasin with lots of storage space against the wall. A large shower as a "walkthrough" or with 3 sides of glass, and a freestanding tub placed in the top left in front of a larger window. Next to it, discreetly, the toilet.

In this context, I would also enlarge the hallway by the width of one wall.

I would make the landing of the stairs one step narrower,

Do I have a knot in my head? A narrower landing would mean narrowing the tread width of the steps coming from the right as well.

Do I have a knot in my head? The narrower platform would then mean the tread width of the steps coming from the right would also be narrowed.

We can't see how the stairs continue and how the head clearance is. Otherwise, I don't think Würfel's suggestion is bad, but "nice" in a new building is still different in my opinion.