If building again - what to do differently?

Actually, I would just add a few more power outlets and change 2 light switches. We canceled the walk-in closet at the last minute, which is a good thing.

I often read about the dressing room. We don't have one, but I didn't have any emotions about it either. For the pro-dressing-room faction: What are the motivators for having an extra room for it?

[*]Thermostats with display

Room-by-room heating load calculation and NO thermostats or as cheap as possible so that later disconnection is not a big problem.

With you, as soundproof as possible construction for windows and wall structure. What is actually the best? Calcium silicate brick + clinker, or filled Poroton and clinker?

Room-by-room heating load calculation and NO thermostats or as cheap as possible so that later disconnection is not a big problem.

For you, as soundproof as possible construction with windows and wall build-up. What is actually the best? Sand-lime brick + clinker, or filled Poroton and clinker?

Oh yes, that is a very good hint, I think I should take another look at windows that are more soundproof than ours. They have a pretty good U-value here, but that apparently means little for sound.
I would also be interested in what the best wall build-up is.
And it will still be exciting in our specific case how to find a general contractor in the southwest who will do the clinker facade on our house :D

Hmm well we have a room-by-room heating load calculation, and one must admit that they are always turned up all the way here, except in the office, which is always set to 0 (because the computers heat the room). :D
I just find the ones with the plastic knob ugly. haha

I often read about the dressing room. We don't have one, but I didn't have any emotions about it either. For the pro-dressing-room faction: What are the motivators for having an extra room for that?

My child sleeps in our bed and sometimes the husband has to get up earlier than both of us. I'm quite glad that he doesn't have to look for his clothes with us then, especially because it rarely happens that he immediately finds everything he needs.

Given your history, I would hire a general contractor or architect who has experience with houses directly next to railway tracks, highways, or with low overflight height right in the flight path. Then consistently demand appropriate sound insulation measures for all exterior components. Additionally, a central controlled residential ventilation system with double telephone sound attenuators connected in series.

And plan living spaces where possible noise sources are far enough away.

Calcium silicate bricks + ETICS or facing bricks is already a good starting point.