I've been to Megacon in Orlando 4 times, and MetroCon in Tampa 3 times. Both have their strengths. Megacon has better booths, but MetroCon has better seminar things.
Regardless Conventions are quite fun. I always feel sad when the convention is over.
I've never cosplayed, but I've gone with my sister who has. I'd like to cosplay, but can't think of anything to go as.