Preliminary floor plan for single-family house

I know I unfortunately can't find the edit button in the first post now. I would like to increase the budget to avoid further discussions about financing. We have now bought the land, which is basically our equity. What the house will actually cost will only be shown by the proper planning. A friend finished building this November and I copied his entire folder with invoices/offers. His house matches our idea of size quite closely (about 181 sqm, with double garage, heating in the garage). I have also been to planners who calculate with 2200€/m2 (Weberhaus for example). There is no upper limit, I know. Even my car already has €28,000 in special equipment and doesn’t even have everything I originally wanted. It’s like everything in life, always a compromise.. Wishes would be outdoor kitchen, new 4K projector Sony VPL-VW52 (costs €10,000). .... oh yes and a lottery win.

I will disclose the calculation in March ’16, then everyone can feel free to give me comments

The main thing is that the vehicle is paid off I am quite similar and want everything and preferably immediately. Also 2..3 big vacations a year and an expensive hobby. However, I also work a lot for it and the price is not low (health, time for family etc.). As an engineer you should earn well...I hope significantly better in Bavaria than here

Yes, the vehicle is paid for.
However, I am already looking for an inexpensive "winter car" for the construction phase, where it doesn't matter if it ends up at the recycler afterwards.
Keyword "Work Life Balance"; Maybe in the future my hobby will be lawn mowing (hopefully not, I would prefer to pave everything).
Earn too little, get enough.
The original plan with which I was with the planner included a home theater in the basement that I had already inquired about at Heimkinoraum Munich, oh yes, and not to forget the car lift in the garage.
I am now so to speak already "reasonable" and can use the 2 weeks I have off to tinker and plan so that I can get a quick start with my ideas/wishes when I meet the architect.

I don't know how long the staircase has to be with a ceiling height of 2.65/2.75 m, I have now assumed a worst case of 4.6 m length.

A comfortable staircase is, for example, 17.9 cm riser height and 26 cm tread depth. You have to overcome the clear room height (2.75 m), the ceiling (assumed 20 cm), and the floor structure on the upper floor (assumed 20 cm) (total 315 cm). This results in a calculated 17.6 steps or a length of 457 cm.

Double garage can also become a "normal" garage with carport.

This will only have a slight effect on the costs, IMHO.

- Is it sensible to design the dressing room as a walk-through room to the bathroom? Who has it like this, who would do it again
- Is a children's bathroom necessary? I see no advantage so far. Up to 10 years they don’t need their own, and for the reasonable period from 14-20 it’s not worth it
- Two doors in the bathroom?

IMHO (!) all frills that I would cut out (even one door is more expensive than the corresponding piece of wall, by the way. And you don’t want a hardware store door. And doors also need space.) By the way, children’s bathrooms also need cleaning, the kids definitely won’t do it! In the end, it’s also a question of money (bathroom equipment is expensive too!) -- whoever has it, can.

- Would you make a sliding door between kitchen and living-dining area, possibly problems due to room height (keyword: extractor hood)

I don’t expect any problems there. The extractor hood will be installed above the cooking area as it should be. The room height has nothing to do with that in my opinion. A great thing would be a double sliding door so that you can possibly have an "open" kitchen (cooking with guests etc.).

- How big should a kitchen be at least if it is planned with a kitchen island?
- If the corridor is too dark, would a glass door to the guest room make sense?

We leave 120 cm space between the kitchen unit and the island. Also think of an open drawer/door or an open dishwasher. I wouldn’t do less than 100 cm. I would not make a glass door to the guest room (imagine a hotel room with a glass door!). A glass door to the living room would be conceivable, also to the kitchen. The front door can also be designed to be very translucent (still opaque).

[*]The thing with the doors is true, even though I want higher doors on the ground floor due to the room height, it doesn't necessarily help to make it "cheaper."
[*]I'm still not sure about the door between the dressing room and the bedroom. Currently, I have a dressing room that is actually my office, and I always get up in front of my better half, who is glad she doesn't hear me in the morning.
[*]The thing with the room divider between the kitchen and dining room is a must-have for us. I've already seen quite a few things online that I like. Another option would be a room divider between the living room and dining room.
[*]The comparison with the hotel hits the nail on the head; I don't know what I was thinking there. A glass door to the living room makes much more sense.
[*]I still have some open questions about the kitchen; I'm not sure if we'll just drive to kitchen studios during the Christmas holidays and see what we like. I can't imagine that the architect already has something suitable prefabricated in his program.
[*]The thing with the kids' bathroom is true. I've also been told that the shower on the ground floor should be reconsidered (cost/space). Personally, I wouldn't have a problem if visitors go to the bathroom upstairs to shower, etc.

Just as a suggestion:
Do you want to always carry the laundry down to the ground floor to wash it and then back upstairs to the closet?
Do you want to always have to go upstairs to shower with a broken leg, grandma visiting with mobility issues, etc.?
How much accessibility do you consider necessary/want to make possible in old age without major measures? (Maybe provision for connections in advance?)
What will you do with the space in old age/after the children move out?
Would you sell in case of doubt if you become too old to maintain the house?

(I don’t want to claim that I already have all the right answers for me to these questions... at least I know that the risk is too high for me to forget to lock/unlock one of two doors in the bathroom – or one of the children)