Variants for furnishing the all-purpose room

There is no more space for tools there, that goes into the garage :p
There is a second utility room area on the upper floor. A second meter cabinet will probably go there. Possibly the controlled residential ventilation system can also go upstairs.
I stick to my opinion: if you want to do laundry in your utility room, then the size is just about okay. You write about misplanning. Personally, I find nothing worse than 20 sqm of empty dance space in the open-plan living area, but not even a second fridge fits in the utility room. I think such planning ignores practical living.

People usually live several lives with different needs – a house should be flexible in that regard. In my opinion, you waste a lot of space for openness in the kitchen and hallway area, and in other corners it is as cramped as in a social housing apartment. And yes, of course everyone has their own preferences – but I can only speak from my experience – in my view the floor plan is not family-friendly like this.

I personally find nothing worse than 20 sqm of dance-free space in the open plan area, but not even a second refrigerator fits into the utility room. I think something like this is planned without regard to practical living.

Exaggerations in arguments are not valid. If you add 5 sqm of your utility room to the open plan area, you still have a large utility room, and your second refrigerator still fits in there, and if you want, any white goods in double quantity. You are still very, very far from having 20 sqm of dance space in the open plan area. You actually have that now in your utility room. It is no art to plan rooms with some air and space accordingly. Furnishing is not planning. Regarding your question:

But the calculation is 'only' 51 sqm. Is that too small??? Are we miscalculating here???

51 sqm is not small and also very generous. However, with a width of 4.50 over 11 meters length... in an L-shaped room narrow spots are alleviated rather than with a parallel layout. As already said, I consider the fireplace to be in the way on one side of the door, and the door on the other. The room could use a bit more space here and there, but not in the TV depth, nor in the kitchen width. And here I am back to the whole house: why planning-fixated only on the open plan area, when everything is still possible?

Why focus only on the open-plan living area when everything is still possible?
[/QUOTE]

We take care of all rooms, even though I have here selectively put only the open-plan living area up for discussion.

There is one premise for us: the parent area downstairs. Why should I put that up for discussion if it is our wish?
We have talked with other parents in real life and weighed the pros and cons. We want to implement it that way. If we have completely planned ourselves out in the early years of the child with this idea, we can still sleep upstairs. The rooms allow it.

As nice as the discussion for the open-plan living area here was, it will probably work poorly for our whole house. It simply is not standard and will be torn apart. That is not bad either; it should suit us. As I have already written once: listen carefully or read well and then select for yourself: does it suit me or not.

51 sqm are not small and also very generous. However, with a width of 4.50 and a length of over 11 meters... in an L-shaped room narrow spots are more relieved than in a parallel arrangement. As already said, on one side of the door I consider the fireplace to be in the way, on the other side the door. The room would benefit from a bit more space here and there, but neither in the TV depth nor in the kitchen width. And here I am back to the whole house: why fix the plan only on the open-plan space when everything is still possible?

About 4.5 m to the TV is already a decent distance if you don't set up a 75-inch monstrosity. And from the sofa, in the current plan, you always look at the table and chair legs of the dining area. But you have probably thought of all that and like it exactly that way.

It just doesn’t really feel right...

The open space is purely square with artificial narrow spots, resulting in the kitchen taking up nearly 40% of the area due to the necessary distances between the cabinets, blocks, windows, and doors. On the remaining area, there is a tough Tetris-like battle for a dining table that works exactly but leaves no room to stretch out with the family and sit more people, and a corner couch that is positioned around a wart-like fireplace and a gigantic TV for an appropriate experience due to the >5m seating distance. The fireplace is, of course, far away from the line of sight from the couch where the family gathers in winter to watch a movie. Unfortunately, the entrance door is disproportionately small and also in the pathway of the kitchen block. If it opens to the other side, it won’t obstruct in the open position.

The statement staircase (which I basically like) becomes a dark ascent due to its central positioning in the house, unless massively brightened by roof windows or something similar, which, however, in summer would lead to corresponding heat or necessary darkening (again no light) as well as massive costs due to the respective size in the hallway. Unfortunately, no upper floor is attached here, as an installed window at the bottom of the plan might also be positively evaluated.
Research what glass surface remains at the entrance with the window width you drew in, it should be around 3 times about a hand’s width of glass each that you have drawn. There is also space under the stairs, should that be used?

The utility room is large, as far as it’s on the base slab, which I think is good, and the non-square room also creates wall space, but why a second door about 2m next to the entrance? Are you sure you need so much space and that the appliances can’t be distributed more usefully according to application?

The parents’ area is the next topic. The bed fits exactly into the room, which is smaller than the bathroom, but the dressing room is one and a half times bigger, yet illuminated only by the hand-width window already described. That will be as dark as a cave. Additionally, one wardrobe (does the door even open?) opens in front of the window, so only artificial light is left. The "catwalk" between the vertically drawn wardrobes in the plan is estimated at 2.5m, which is also too short to receive the lady of the house in the evening in a glamorous and seductive manner, but at the same time wide enough for another bag of chocolate candies to lie next to the bed. Compared to the used space, you have created little closet meters and these are distributed unfavorably.

All in all, the proportions (whether within or cross-room) in your design just don’t work for me, your ground floor provides over 40% of the space for utility areas (utility room, hallway, staircase, dressing room) (60 to 75 sqm remaining). Space for storage, staircase to get to the next floor, etc. is needed, but the question is whether it forms a flowing transition to the living area and is accordingly integrated and upgraded or merely present because necessary. It feels to me in the two upper designs that it rather bears the quality of necessity than staging. Best example staircase: basically upgraded by the landing but degraded to a means to an end due to the dark and hidden position in the center of the house outside the sight lines.

If you attach the upper floor or your ideas, it will probably be easier to continue working here. In addition, there would be some fundamental approaches that could make building simpler, such as optimized routing like short (water) pipes, walls stacked on top of each other for easier statics, etc., orientation on the plot, driveways could also be interesting, after all, you are building over quite a bit of area with your design.

The exaggeration at one or another point is meant just for entertainment ;)

I once marked a walking path from the parents' bedroom to the children's rooms upstairs in a large open space. You can do that if you don't like your children and enjoy bruising your shins green and blue. :) I understand the desire to put a floor between yourself and teenagers - but that's still more than 15 years away,...