I have had some good times at the Foundation room!  
Great crowd - not overly crowded but full - you can still walk around with out pushing people.
Unlike the other clubs, it is more a social house where friends meet up to share some chat over drinks, enjoy the cozy dance floor, and step out side to enjoy the balcony, which has a great view of the Strip.  
It is not as loud as the big night clubs and the balcony gets the fresh air in, so not sick smokey.  
One time I saw a guy there who I swear was Bruce Willis' twin!  
or ?  
 Definitely should check it out