So let's get this clear, I have never organised a meet up or an event,so this is a challenge for me, but I think what we are trying to
achieve is possible.
While thinking through my strategy about creating a superswarm I came to the conclusion that there are two completely different approaches to the type of event:
1) Are you going to get people to come to a one off place and get your swarm together a little bit like organising a flashmob?
2) Piggy back on an event with a gathering of people who are already there or planning to go eg. a football match, festival or exhibition?
There's a great story here of a restaurant creating a one off for their occasion.
So for me its without doubt option one - create a unique event. This needs far more work because you have to deal with the when, where, why and whether you need to incentivise people to come.
I believe foursquare should actually be able to change social behaviour and the delight of the users meeting other foursquare people makes that become the event. This makes the planning harder but the result better.
Next, where should we hold it?