Floor plan 2 full floors KFW 55, 136 sqm flat roof

Much has already been said. Even though I can understand your thoughts, there are bottlenecks that cannot be explained away, and these are "privacy for you as adults," storage needs, and the orientation of the windows.

Stairs are nice and pretty, but unfortunately also a space eater. If they start from the living area, it eventually leads to a lack of privacy, namely for you seeking peace and quiet, as parents who want to retreat from everyday life and the evening hustle on the couch. I see less of a "sleepwear" problem here ;) (there are also nice designs, etc.), but simply the situation that it can be annoying when two teenagers repeatedly want to go upstairs with friends or into the kitchen. Also, when rearranging furniture (sofa against the wall), the visitor’s view always falls on the sofa. You might experience that 3-5 times a year, but over several years with two teenagers, that will be wearing on your nerves.

It’s enough if you ask me, too little if you ask my wife. More space also tempts you to accumulate more stuff. :) There will still be a 3x3m storage room behind/at the carport.

Well, you don’t even manage to fit the bare essentials. Your wife is right: the utility room will initially be full of technology. Then there are the washing machine/dryer units. And where will the delicate laundry be dried? Under the stairs? In the guest room? In the upstairs hallway? Where do you store things? Where do you keep tools and spare light bulbs? Where do you put the Christmas decorations and so on? I’m linking here to a collection of what there could be. Not everything has to apply to you, but many things over the time you live in the house.
https://www.hausbau-forum.de/threads/die-liste-die-jeden-bauherren-zu-interessieren-hat.34418/
You don’t even have an attic. You basically have nothing except a corner on a pipe or in front of an installation in the utility room, so more likely a bag on a pipe, a box on the hot water tank, or a step where the collected empties stand underneath.

Pantry from the kitchen, which would also be more practical.

You don’t need a pantry under the stairs. What should go in there that won’t fit in a tall cabinet? Put the missing wardrobe under the/one stairwell, because I don’t see space for various jackets and shoes. Surely you can put a wardrobe in the guest room, but with kids and various shoes, this closet will quickly be overfull as well.

Regarding the orientation of the windows: You have really great window areas that open the house to the garden, make it appear bigger and friendlier, and provide brightness. But have you looked at your south side? It would be understandable if you wanted to shield yourselves from the street, but there are neighbors on both sides as well. They literally look right into your lap with the railing-free windows on the upper floor. And unfortunately, the carport stands in front of some windows, the shed will block additional windows... If a vehicle is in the carport, the postman or visitors can hardly reach the front door.

I would probably… hmm, I would probably rotate the house with the long side to the front and back. Capture sunlight from the south, but switch to windows with railings.

I just don’t want to always see the dining set from the couch.

Then make the living space L-shaped, kitchen up front with a strip of windows and lots of cabinets if you like. The dining area has the most space and light in the corner, the living room then separated by a small wall section with the TV on it. That way you get privacy from the sofa toward the dining table and not the messy kitchen. Guest room NE, utility room SE... a two-quarter-turn stair. That fits well. In front of the kitchen you could create a seating area with a hedge—if necessary you could put the front door there…

There are many floor plans that then obviously look somewhat boring because they are very common, but they work better because you’re not stepping on your own toes. Personally, I’m not a fan of a lot of hallway, but you should simply allow yourself that. It doesn’t have to have a door everywhere ;)

If you move the house three meters further back, you can also enter the house space-efficiently and practically through the front door without having to walk through the kitchen with dirty shoes.

Honestly, the utility room is too small for me too. I wanted 10 sqm, but the planner didn’t include it or overlooked it in the first draft.

Nice if you could still get a storage room for suitcases and such upstairs. With a different hallway area, this is quite possible.

In this respect: I’m also in favor of a reset :)

Straight staircases are nice and pleasant, but unfortunately also space eaters.

Single-flight straight staircases are a feature from the moth tool kit of replacement villa sellers, selling the cheapest construction as noble formal clarity. They are (except for their unfavorable traffic-related shape) absolutely not bad, but completely overrated.

They will both rather be placed by the bicycles and trash bins behind the carport, because the boiler doesn't fit through the door to the utility room,

Before installing the door, everything still fits in. And if it ever breaks, it has to go through the window.

If you don't want to look at the sofa from the dining table, try an L-shape.

Dining tables need a lot of space, but not without reason. By the way, it's nice that this was taken into account here and that they didn't just insert doll furniture as placeholders. You have to mention that sometimes, someone has thought along. Benches or, in your case, window seats save space but are not necessarily practical or comfortable. I find the window seat okay for lounging and reading, but leaning back after a meal or during a chat with friends is uncomfortable.

Thank you, yes, you actually understand quite well where my imagination is going.

I try at least, although with tight spaces you really have to look closely. There are dimensions in construction that should not be undershot, but just as well there are dimensions and constellations that are absolutely individual. At the moment I am happy that some things with us feel freer and more generous than I feared; my wife obviously has the much better eye. For a while our idea was to place the dining table in the corner of the staircase, so the sequence kitchen-living-dining, for which I would have surely been slaughtered here :D but apparently we two have a peculiar way of life. But you also have to be careful, because you can quickly create something crappy that you remain dissatisfied with, so I was always especially grateful for clear criticism. And... we no longer have children in the house! Let go of the staircase shape completely and already there are new possibilities. Be "honest" with yourself regarding storage space/room for keeping things, although you can also "enthuse" children about that. We have a 6x3 storage room in the soon-to-be-built carport, expandable if necessary, because I don’t necessarily need a covered parking space. I find "compact" floor plans nice but they have to be especially well thought out and some sqm (e.g. utility room) simply have to be there. For example, in our case the hallway is open to the living area but you have to like that too. Take your time, read through the critiques.

Access from the street may be a maximum of 4 m wide

And another note: an access is not a driveway. This means: your sidewalk, wai, will be lowered to 4 meters wide. After that, your paving or the courtyard/front garden surfacing or design can be dimensioned differently. If there is any uncertainty, ask again. But why limit yourselves with the paving or parking space if you could also expand a bit.