All the parties I've been to have been retarded. They're mind-numbingly boring. Yes, I've been to huge parties with 400+ people and gallons upon gallons of alcohol too. Most of them turn out to be sausage fests >_>. My friend's last night turned out to be ...this hot chick even said it. My friends and I were playing cards instead of playing beer pong and she was like, "why aren't you out there socializing?" and I was like, "i'm not gay."
I've been to big parties like that, and you're right. I just think some girls are too scared to go because there are so many guys. I'll be the guy sitting in the quieter room smoking and drinking with my buddies. I prefer small gatherings of friends, which usually cosists of an even ration of guys and gals.