In my personal opinion, I think that teenagers aren't too picky and will eat whatever is available. But I think what goes well are "party"/snacking foods. If you don't know what the teenagers will like, try having several small items for them to choose or stick with the "classic" foods that everyone likes. In case there are vegetarians, be sure to have an option for them:
Chips, cookies, and crackers
Pizza: Cheese, pepperoni, sausage seem to be the three favorites.
Mac and Cheese
Burgers and Fries
Nachos:Leave out ingredients and have them build their own creations
Ice Cream Sundaes: Leave out ingredients and have them build their own creations
Sandwiches: Leave out ingredients and have them build their own
Spaghetti and Meatballs:Serve meatballs on the side in case of vegetarians
Breakfast items: French toast, pancakes, eggs, fruit, etc.