My duaghter is also 15 and last year she intially opted not to do the wild side, but the counselor on board talked her into it... it didn't hurt that she thought he was cute and loved his accent!!!
That being said, she just barely managed to get into the excursion because it was full, but she said she had the BEST time EVER on it... she especially loved the snorkeling and kayaking ... she was able to see lots of interesting things, and loved hanging out with friends she made on the ship...
which, by the way, she still keeps in touch with...
so, YES YES YES YES!!!! you should goooooo!!!! It will be awesome, and don't tell Disney, but it would be worth twice the price!!!
GO FOR IT!!!