Instead, I just put a system which checks to see if you are within a few squares, and engages that object in an interaction. In the case of NPCs, they have special code (a bit of a hack) to detect when this happens, and stop and face you.
Other than that, I've begun putting in people's basic schedules. I'm going to have to put "interruptable" events, which are random schedule blocks that can happen given certain triggering circumstances; some fun ones, characters maybe will get up in the middle of the night at random times and go stand behind their house (relieve the bladder), but also more mundane things like to go to the post office during the day.
The system has a few bugs that I'm going to have to work out, but it's happening! Still not handled are doors, but that's no problem because I haven't put any in yet! They will have to be handled automatically, at any rate, maybe by specially calculating pathways with all doors "open" (this is actually sort of tricky though) or maybe by encoding some more information about barriers that are "passable", i.e., by opening the door. So the pathway consists of possibly opening door X on your way from point A to point B. This is a bit of a hassle too. We'll see. It really only has to handle doors for right now, though, so it's not a problem.