In your third pic install over stairs (near light) as smoke will go straight up, or even install center of hall so they are between the stair railing/cabinets, in 4th pic move them near light also at stair landing (in hall in front of landing step a few feet out or so)
Install at/near stairs/landings , bedrooms, any others can go anywhere you want (center of rooms recommended)
For example (photo/heat and ion/co2), notice they are spaced for optimal coverage (open floor plan). For every co2/ion, there is a photo/heat not far.
1st flr
2nd flr
Third flr
