Plant planning - window arrangement upper floor south - cost difference large!

I discussed it intensively again with my wife. We will probably choose the large windows and design a module so that it can later be replaced by a door. This way, we want to keep the option open that a balcony could still be installed later.

I would build windows with sills in the children's rooms. Whether through window height or balcony would not matter, but I would not create a connection between parent and child through a balcony.

The compromise now is that we will design the windows as seat windows with low sills