I've only been to 3 different events, but they've all been very different in terms of setup.
Went to a county geoevent back in June. We met at noon, got passport-type things to mark with stamps from temp caches, and went around to find the temps. 12 temps, with a bonus 13th. However many stamps you got translated into raffle tickets [you could also just buy the raffle tickets]. We ate as a large group, which was awesome, took the event picture, and did the raffle. Fantastic time.
2nd event was GW9 this year. Socialized with cachers and everything, but my mother and I went off separately to find some AGT caches. We met up with other cachers who were in town for GW9 when we went to our caches, but that wasn't sponsored by GW9. We just did it of our own accord.
Last event was cacheball the day after GW9. We sat around in a group and talked for a while, then we all played wiffleball.
As you can see, basically the only requirement is that cachers get together to interact. Or that's how I look at it.