I haven't ever gone to one but I've been invited to plenty, because I A: play table top RPGs B: am a girl and C: have a wardrobe quit suitable for LARPing Vampies.
I think it could be alot of fun.... With the right group of people. Most of the LARPs I was invited to were the kind where the guys wanted to hook up "in game". ( Not saying all LARPers are pervs, just the ones I knew).
If you play table top with a group you could always try to take it the one step further and LARP a campaign, see if you like it.