For different teen parties in the past we've done the usual pizzas, hamburgers & hot dogs, or taco bars. We served them with all with the normal accompaniments.
One of the best responses was when I made a really simple vegie tray (meaning not "fancy" vegies", heavy on carrots and celery) and in addition to the typical ranch dressing I put out small bowls of peanut butter, cream cheese and raisins. The kids were having such a good time making "bugs on a log" and reminiscing about their younger days. It was really cute. There was also a fruit tray and I couldn't believe everything that was smeared with peanut butter.
We've also done make your own brownie ice cream sundae bars or fun cupcakes instead of cake quite a few times.
Ah, memories of good times with the kids! Enjoy your time!