I assume Foursquare faced this issue. You've got a social service that is location based but requires a lot of users to make valuable. I'm in a similar boat with an upcoming start up, and I'm trying to figure out how to role it out.
Do we launch and try to hit a group of specific users in a small location to get them using it and hope it spreads from that location?
Do we try and do global all at once? In my location Foursquare was useless to me for about a year.
Not sure if we can hit multiple small locations... Any strategy tips would be useful.