I wish this feature were better implemented. It seems like an after-thought bolt-on to vBulletin. Stuff posted in these groups doesn't appear in MyFlyerTalk or generate any other sort of alert, so it's too easy to forget about them.

For my situation, the Alaska Airlines Lounge Thread serves as our default "Geographical Social Group," but that's largely because the AS route network means that most people who frequent the AS forum are in a relatively confined geographical area. This is not really an exportable model to the other major airline forums.

Perhaps something better will come along in the future...