"Locative social media is especially interesting because it directly affects how people move through the city. It can be terrifically fun and useful for people who fit its prescribed social model." This kind of proscription (or encouragement) of behaviour is interesting, and I think there are a variety of ways to do it "sensibly". And: how did you expand the group of "people who fit its prescribed social model"? Small changes of behaviour, amongst larger groups, are much, much more interesting.