One of the biggest things we need for Teens is, oddly enough, a feature that lets you send a sim off the lot for a set amount of time (not work, just something to get sims you don't want in the way out of the house). Then you can send the parents away for definite period of time and have a Wild Teen Party! What would also be a cool addition to that feature is that siblings could call the parents and spill the beans to trigger a sequence where the parents come home, clear the place out, and scold the host! Now that would be awesome.