Casa 92 is certainly one of the best clubs in São Paulo today. It's placed in a big house (hence…read morethe name "casa") where each room is either a different dancefloor or a bar or a place to hangout like a pool table area.
There is even a little store where you can buy souvenirs from the club. Also inside that store there is a bar, which is normally less crowded. So go there if you don't wanna wait in line for a drink :)
The place gets really crowded, so be sure to arrive early. Also, send an inbox message on facebook to their page - Casa 92 Oficial - until 6PM and get better prices on the entrance fee. Usually, women can get in for free til midnight if they have their names on the list.
In Brazil, people tend to go in an early age to clubs and sometimes other clubs are full of underaged kids. But Casa 92 is one of the few exceptions that you won't see many teenagers. The average age is 25-35 years old.