Depending on the layout of your apartment and the ceiling height, the bikes can be hung vertically or horizontally (in either the upright or lay-down position).

All of those positionings lend themselves to hanging from the ceiling, so I can see no advantage to using a wall-hanger instead of simple ceiling hooks. In either case though, the attachment needs to find a joist or stud.

Hung from the front wheel, the bike can be almost flat against a wall, or two or more bikes laid against the wall like overlapping shingles.

I got 22 bikes along a 17-foot wall, still easy to remove and replace one. Note that this room had only a 6-1/2 foot ceiling height, but still has some room underneath the bikes for bagged stacks of tires and "under-bed" storage Tupperwares.

If I may make one suggestion, it is that this is what your apartment should look like after N+1 has had a good run: