I don't know, I've done a lot of 8 - 12 hour gigs and I've never run out of music. It helps to have lived through decades of music and to be familiar with what has lived on through TV shows, commercials, movies, and sporting events.
I try not to get reminiscent in my sets with young people because, they haven't lived long enough to be nostalgic. What I call a throw back is fresh to them if their exposure comes from the media and internet. So, to that end - the mixing of old and new tracks spontaneously is completely transparent to them if the recurring oldies still hold a place in current youth pop culture.
The girls are the ignition and the boys are the fuel so, always appeal to the girls taste first - and then the boys. A dance floor full of girls is more reliable than one full of boys - and the boys won't be leaving if that's where the girl's are at.
Advance lists can help - but, it's rare to get one that wasn't drafted by one person, or a few confidants. Every school has it's own culture too, I've had some interesting experiences where the kids were more into Bob Dylan, Grateful Dead, Reggae, etc. (stuff their parents obviously listen to) than any of the current pop music.
There's less and less commonality these days - music taste is incredibly splintered and individualized.