3Dan:
I'd post on the Cruise board asking if there will be other teens on DVC cruise. You may want to start a thread as some are verrrrrry long and don't list ages but only that they have kids.
I do remember that they have a teens only area onboard from our last cruise, but since we are empty nesters, we only noticed it in passing.
You will have a terrific time just watching through the eyes of your guests, we've done this before and to me it is almost more fun watching their joy.....notice I said almost.
Happy memory making!