Floor plan of a single-family house just before final design - Please provide tips and advice

You’re not seriously moving in where you keep your wardrobe and office?! One can keep some dignity in old age!!!

I don’t think anyone can say where they will end up in old age. If one is lucky enough to reach advanced age.

And if the in-laws or whoever move into the granny flat, you won't have a guest WC on the ground floor anymore?

And if the in-laws or whoever move into the granny flat, you won’t have a guest WC on the ground floor anymore?

Yes, we have to do without it.

Yes, we have to do without that.

And the in-laws share the one bed? Or is only one coming?

For 650K - goodness gracious. Honestly, in my opinion, that is totally underdeveloped - you can't build a house like that. It won't just sort itself out or anything. If you plan rubbish now, you'll get rubbish. Plain and simple!

What for, to get to the play equipment? ;) So terrace and then another driveway that makes the "garden strip" even narrower? But post it so we really know how it looks.

The driveway and the garage are already there. You could possibly park a motorhome or something similar there.

For 650K - manoman. Honestly, in my opinion this is totally underdeveloped - you can't build a house like that. It won't just work out or anything. If you plan crap now, then you get crap. Plain and simple!

I know the floor plan is not optimal, but I wouldn’t dismiss it completely as crap.
For example, I like the rooms upstairs. If I change the stairs, then the rooms upstairs won’t fit. The granny flat is only part of the floor plan. That’s where our office and guest WC are.
Our main living area is the kitchen and living/dining area.