Regarding the question of heating in the south, I would anyway recommend integrating cooling into the underfloor heating. We can only report positive experiences with it. Additionally, shading from the outside should be possible. Personally, I am not a fan of floor-to-ceiling windows on the upper floor. But that's a matter of taste. This way, the children's rooms are the nicest rooms on the upper floor - bright and friendly - ideal for playing or learning to write.
Alternatively, I also have this variant with a master bathroom, although the utility room would then be above the living room. However, this line is not quite as thick. I could imagine that it would disappear behind a drywall installation.
