Steve
Well, Center City restaurants won't be inexpensive. So for 12 people, you will pay a fair sum. But if I was taking a group of 16 year old kids into the city, I would most definitely consider El Vez: It's a really fun place that kids that age would really like. There are plenty of great places in the city - Parc on Rittenhouse Square is also nice and might work for a 16 year old's birthday party - it's patterned after a French country restaurant: I like Pizzeria Stella in Headhouse Square and that might also be a great place for a group: Any place might be willing to talk about a group meal with a reduced menu on a total price or price-per-person basis. In any case, call first for such a large group.

Trisha W
The obvious would be Dave and Buster's But dont forget South Street, lots of decent places down there Our kids enjoy going to Hibachi (attached to Dave and Buster's) Mixx in Chinatown is an awesome sushi joint And Golden Gate in Northeast is cool for Russian dining. All depends on the taste of your daughter Maybe update us with what type of cuisine she wants, i can help narrow it down.