Solid house-single family house 142 m² living space, questions about floor plans/building costs

After having considered it back and forth several times, we have now had a floor plan made that suits us. (Staircase faces north)

In the floor plans, the living area has shrunk to 132 sqm, which should also slightly reduce the overall costs. What do you think of the floor plans? We are still not quite satisfied with the arrangement of the sanitary fixtures on the top floor. We want a floor-to-ceiling, tiled shower. However, in the arrangement according to the floor plans, it takes away quite a bit of light from the washbasins. Do you have any ideas for a different arrangement?

Do you really need the tiny guest room upstairs? I would sacrifice it in favor of the children's rooms...

In the bathroom upstairs:

just swap the shower and the washbasins...

Downstairs:

Why not an open kitchen?

@Mycraft: We need the guest room for when visitors come occasionally. Also, we want to use it to store the printer, folders, etc. Originally, we wanted an open kitchen, which would have opened up the entire ground floor. However, we changed our minds because of the smells. Additionally, we need the extra wall for a large bookshelf.

I would also swap the shower with the washbasins, as Mycraft suggests. Otherwise, the design seems functional and okay to me as a layperson.

I would also swap the shower with the washbasins, as Mycraft suggests. Otherwise, the design looks functional and okay to me as a layman

When swapping, the shower side wall must not be built either, as this would also block natural light. Additionally, it could become very tight with the door.

When replacing, the side wall of the shower must also not be built up, because then daylight is missing as well. Also, it could get very tight with the door.

Yes, the door is annoying, but so is the sink there. You could also shower with a spot above... Somehow I find the three objects very cramped on the wall. Maybe you could move the tub to the exterior wall, move the toilet to the 2-meter limit, and place the shower next to the toilet (move the door)???