I have no prior experience in organizing this sort but if thing, but uh, here's a new MeetUp I'm starting.
BAMF - Bay Area Members of the Fediverse
http://meetu.ps/c/3CrlC/vlXjp/d on Meetup
Currently testing it out to gauge interest. If you live in the San Francisco Bay Area and want to come out and make new friends, that would be the most amazing thing. You are welcome to join, regardless of whether you're from #Diaspora, #Friendica, #Hubzilla, or any other federated platform.
I'll pick a date and a venue soon.