My dh and I took friends kids with us to DTD and PI in February they were 11 and 13. Admission is free to PI but you have to pay a cover or have a pass for the clubs. Personaly I would not have felt comfortable taking them to any of the clubs but they had a great time at DQ and the magic shop, we did some shopping and some line dancing at the west side stage. While we saw some "bar type activity" outside it wasn't to bad IMHO and they were fine with it. I think a night of shopping at DTD, a night at DQ and a night at the Boardwalk would all be fun for teens.
I have seen teens at CW and AC but depending on the cast they may or may not tone it down ~
The boardwalk has great pizza, carneval games and some great restaurants and shopping. My DN can spend all his time at the ESPN club as he is a total sports nut. They can also rent a surry bike and do a few loops around the boardwalk, beach club area.
You may find with EMH a park is open late each night as well and the arcades at the Contemporary, Polynesian and CSR are worth a trip - esp for teens.
TJ