An airport fits the definition pretty well

Yes.

But one can be a bit more specific and think of their long corridors as liminal spaces, but the cafés and stores in them as not. I flu a few times per year out of the same airport, and typically wait in the same café for over one hour. I use this time to rest a bit before getting on the flight and eat something, and it doesn't feel liminal at all.

Flying into small fields in a small plane can be an interesting experience; some are actually quite busy, they'll either have a popular mechanic shop on the field, a busy local flight school, or it's a destination for business jet travel because of a local golf course or something. Others are almost abandoned, which can be an interesting experience to visit.

Yes. Especially the bits that connect multiple concourses on foot.