Floor plan of a single-family house as a wooden house on a ground slab with carport

In the original plan, we had planned a window seat at the dining table on the south side, but then removed it again because we thought the sun could be too glaring there, especially in spring and autumn. What do you think about it – would it do the room good to have a window there? It could theoretically also be a double window like in the kitchen, so that a classic corner bench (or chairs) could be furnished there.

Seat windows are not suitable as permanent seats. There are problems for the person sitting there (uncomfortable, hard glass). There can be problems with the glass (heat buildup if something is left lying there in an unfavorable way).

Therefore, I would not put a seat window there.

A normal window: I think it’s a matter of taste. According to the plan, there are almost 4m² of glass directly around there, so it will be quite bright in terms of light. If anything, I would rather convert one of the doors into a window (floor space) and then possibly install another window depending on the façade design.

PS: South-facing windows cause less glare than east or west windows (the sun is higher).

A bay window usually takes up living space because of the protruding window sills or wooden framing, which must have a certain depth to be truly usable as seating. Of course, we also considered something like that but decided against it because it looks nice but is completely uncomfortable, cold, or hot. Our large fixed glazing sits outside on the masonry, and so we have a deep windowsill there about 40 cm high. Even though it would now be possible, no one has come up with the idea to sit there yet. I would leave it like that.

Corner bench in the dining area (yes, impractical for many people, but we are usually four; it is a childhood memory we want to keep)

I understand that, and especially then you should have very clear ideas about what and how you want it. Ideally, you already know which bench it should be; then you can nicely adapt the area around it (including the window). Currently, it seems a bit cramped to me; it is also nice when usually 4 people can sit generously. We have, for example, designed the whole area comfortably there, for example with a dining bench, and you should find out what distances your sitting/dining requires comfortably. If a lot of glass is important to you, which I can well understand, I would move the dining table into the currently rather empty-looking area and use nice dining bench(es). Try reconstructing that at home and measure precisely. Maybe you should also omit a door opening, for example from the dining or living room, and rather take generous fixed glazing because doors also take up usable space; in my opinion, two exits are definitely enough.
I would also like, for example, a really large fixed glazing, not floor-to-ceiling but with, for example, a 40 cm high base, similar to a bay window but without that protruding bench.

Furnishability is not yet 100% clear to us

Only you can clarify that through your needs, but it is extremely important. Sure, you can arrange everything somehow later, but it would be nicer if

it would do the room good to have a window there?

The question is also what I see when I look generously outside there? If, for example, you can deliberately place beautiful plants or the like there, you will always like to look outside; if there are only bikes or a wheelbarrow, then a wall is probably better, with a picture inside.
If it fits exactly and covers your wishes. You can still shift a few centimeters each way.