Floor plan: who has the master bedroom on the ground floor?

Here, as requested, the upper floor.
For explanation:

Hobby = office
Office = child 2

What will still be changed:
- the airspace in the hallway will be reduced in favor of the office.
- the bathroom furnishing is so far only exemplary.
- between the two bedrooms there will be only a lightweight wall, so that if we do not need these as bedrooms, we can create a large utility room for hobby, party, whatever.

and yes, we know that the bedrooms are not the same size ;-)

Hello David,
I have read your initial post and can understand the draft well based on these requirements as well as the low priority you have given to the design of the upper area so far.
As of today - if still without a child - you actually don't need the upper floor.
I would therefore only do what is statically necessary on the upper floor and install a bathroom that is child-friendly if the need arises. Set up your office in the large room that is created and consider a children's room only when it becomes necessary.

In the area "Sleeping - Dressing - Bath" I see room for improvement if age-appropriate living or living with a disability is to play a role: passageways and maneuvering space are too small for that. The space between the closets in the dressing room is an adequate hallway but not a place where people with normal joints want to change clothes. Maybe someone who has such a dressing room can report on everyday life with such a room after a few years.

Since I have been using a corner bench in various shapes for over 30 years, I believe I will like it for the next decades as well :)

However, I would not let this corner bench influence or dictate the windows, as I have already said. That would be my personal opinion, that the windows on the south side look strange inside without this fixed furniture. Chest-height windows directly next to the patio door...
Besides, it should still be possible to place an independent dining table. If you look at the design, you realize that rather than spacious rooms, it forms corridors and passages.
Here there is a long two-line kitchen, a corridor in front of it that is just leftover space. The dining area is L-shaped.

this should definitely remain separated from the living area in the north.

Of course, it should also be separated then. If you name one element that should be changed, that naturally means an adjustment and almost a redesign as a consequence.

it will be:
- the open space in the hallway is further reduced in favor of the office.

That is better. What is the open space in the hallway good for? I see no attractive gallery, no special hallway. The draft from the front door goes up, noise as well. If the child’s room is then ever used as a child’s room, it will not have it easy.
What about the idea of the granny flat? That is not feasible as is.
But back to the windowless kitchen: it will remain a dark hole. The counter, that is, the island, is already far from "bright" because it is too far from the patio door — everything that is then positioned "at the back" in the kitchen is misplanned here. Maybe the staircase is placed here, maybe also the access to the garage, i.e., the hallway, and everything else is moved to the positive side. In my eyes, there is still a lot of room for improvement in the planning. Personally, I would not have submitted something like that.

There won’t be a pool party every week – but it would be practical if guests could go directly to the bathroom and not have to walk through the house in wet swimwear. Or am I mistaken?

Only that I suggested placing that rare access to the east. A bathroom with a south-facing window is not always a pleasure.

For us, it only contains an office, two possible children’s rooms, and a bathroom, distributed over more than enough space.

It’s not about space; it’s about the stair location, which affects both.

Your original question was about the bedroom on the ground floor. I’ll put it this way: the house is not a masterpiece (you have to, or I have to, look twice), the attached sleeping wing in the east is hardly creative either.
The house consists of several hallways: the one from the garage, the one from the main entrance, access to the multi-purpose room, between kitchen and sleeping wing, the dressing room. And the more you look at the plan, the less sense the slalom corridor from the hallway around the kitchen makes, which really shouldn’t be there. Somehow you never really arrive anywhere in the multi-purpose room; only paths are constructed instead of arriving in a room.

Hopefully, the load-bearing walls are load-bearing in the basement, because there is no unity between ground floor and upper floor, right?
In the upper floor, the shower is even wrongly marked under the slope; the bathroom is drained through the bedroom on the ground floor. You just have to know that before you wonder.
I would like to be more constructive, but that is not possible due to lacking knowledge about the development plan, the neighborhood, etc. I see another planning round ahead.

And a double garage is absolutely necessary? I would consider a carport/partial carport garage in favor of a kitchen window (or gaining daylight in the west, no matter how the floor plan is or will be), as the double garage really dominates the house.

Spontaneously there is not enough space downstairs, upstairs there is too much. Kitchen too dark.

I will take a look at everything later.

Just something to think about. Do you want to sleep in the attic if there are children someday? In the first years it is very impractical to sleep on 2 levels.

Spontaneously, there is not enough space at the bottom, too much at the top.
Kitchen too dark.

I'll take a look at everything later.

Just something to think about. Do you want to sleep in the attic if there are children? In the first years, sleeping on two levels is very impractical.

Yes, the option should exist to sleep upstairs for a limited period if there are possible children. Then the office would have to move to the ground floor bedroom for a few years.