Well, I can't really recommend Mensa. I found that most of the members weren't particularly interesting after they started repeating their party pieces. They liked playing games, both on and off paper, whereas I prefer to do something more useful with my life (plus I'm not very good at the games they played
Their attitude towards intelligence was disappointing. They appeared to believe that a high IQ is both necessary and sufficient to do well, in much the same way that an immature teenager thinks he knows how to drive because he has a car with a big engine.