We've been on many trips to WDW with our children as teenagers ... in fact, we are going again in March and they will be 17 & 18. To be honest, our teens like to do the same things that we enjoy. Parks, rides, swimming, water parks, resort hopping, etc. We've taken them to PI and go to the comedy show and Adventurer's Club too.
We usually make a trip over to Cocoa Beach and Ron Jon's. Last two trips we went on an airboat ride (Old Fashioned Airboats) near Cocoa. One year we went to a Tiger's baseball game in Lakeland. One year we went to Kennedy Space Center. For the most part though, we spend our time at WDW.
Once in a while the kids take off on the bus to a nearby resort on their own just to check out the shops, but for the most part, it is a family vacation and we accomodate everyone's expectations for the trip together.
Our family vacations are a chance to bond and reconnect. (It helps that we camp and there is no TV or computer!!) To be honest, I enjoy spending time with my kids more than I do other people.
You may want to find out what your kid's expectations are for the trip and try to factor those into your plans ... but do it as a family -- they grow up so fast.
