Bungalow floor plan 160-170 sqm with basement

If you really insist on having a basement (I understand, the look), then carefully consider whether it should be a full basement. Then also whether it should have natural light or not. That makes a huge difference in price. Sauna room and technical equipment are packed into a small space. An office (which you had planned upstairs) would make sense downstairs as well; nicely furnished, it will also be cozy there. A guest room with a small shower bathroom also doesn’t take up much space. I’m estimating about 70-80 sqm. Then you can still consider giving the office and guest room natural light through light wells. Always keep in mind that light wells take up a lot of space. I don’t find them particularly pretty either.
I think every basement should have its own entrance. Cleverly divided, you could save yourself a light well.
I would really recommend planning all relevant rooms (bedrooms and kids' rooms, guest bathroom, main bathroom, storage room) upstairs. The rest goes downstairs, and where there is still some space left, you can get good storage areas through cleverly planned cabinets.

I had spoken of an idea "a la Vita, Weiss" and also implemented it:
Of course, I also had the desired basement in mind... but I have to say, it is quite difficult to conjure up in the ground floor, that is a bungalow with so much space, in the "middle" of such a space-consuming house without creating endless corridors or dark niches. The basement is all unsatisfactory. The rooms are dark inside, even though a light well is installed there and a panoramic window is present. An apartment there would only be possible with effort, and then only with closed eyes.

Well then: I have succeeded somewhat in the approach. Everything under 15 meters side length. I haven't looked at the area anymore... and also light wells, the basement terrace mentioned by the TE, I no longer see those with the floor area ratio. The house uses up the entire plot in terms of area, it feels like: in front and on the sides 3.7 or 6 meters (the light height also requires boundary distance) mean that the garden hardly remains at all.
I will spare myself the details in this regard - the co-discussants know about such a problem - ultimately the TE must know how to position the house on his property.
The only thing I logically moved is the terrace into the southeast. Since it is covered, it is at least wind-protected here; a southwest terrace would be windy and the roof would not help. Also, I wanted to do something nice for the children with the west side :)
But basically, the designs could be countered, the garage could also be shifted from west to east.
Much is of course dependent on each other, so shifting this and that is usually not possible without something else no longer working optimally.
As far as I understand, the children do not need their own bathroom?

So here are the designs. Note: interior walls only measure sketch-ready 10cm, the exterior walls 38cm. The kitchen island is 2.40 long, the bedroom windows 1.80 wide, the panoramic windows measure 3 meters.
Up is of course north ;)
I am still here for any questions :)
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And here is my favorite (if I may say so), slightly modified:
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I also think that's best, maybe move the children's rooms closer together and put the children/guest bathroom by the hallway, otherwise the guests will look for the toilet behind every door ([Wasserfall ist ja nicht so deins])

Definitely better and the separation is stylishly done. But it still meanders way too much for me. Looks like the floor plan of the Palace of Knossos again. :) Or those labyrinth games with the little metal ball.

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I have to say, this one appeals to me the most (but you can also work magic!). However, I also love the concept of the bungalow (all together next to each other). I like that I don’t have to walk through the whole house to get to the children. I might possibly remove the wall/door to the hallway and at least let some light in that way.