I'm in that group, and I don't find these services particularly compelling either. Maybe you need to add "extroverted" to your list; I'm not sure. I tend to have a smallish number of people I'm really interested in hanging out with, and we just coordinate directly.
I did spend some time using an earlier location-based social network and the problem it had was this: you don't know what check-ins are general invitations to come and join them, and which are purely habit (or in the case of 4sq, competitive). I, personally, was never confident of the etiquette, so generally avoided just dropping in at places where someone checked in.
I did spend some time using an earlier location-based social network and the problem it had was this: you don't know what check-ins are general invitations to come and join them, and which are purely habit (or in the case of 4sq, competitive). I, personally, was never confident of the etiquette, so generally avoided just dropping in at places where someone checked in.