Hi. My DD is seventeen. We have been going to WDW three times a year for the last few years except for this year. We haven't been since last June because we are planning a four week trip in May/June.
That said, she (and her friends, since we usually take one or two with us) LOVE the parks. Their favorites are the thrill rides, TOT, Space Mountain, RR, EE, etc. but they still love the classics too. Haunted Mansion, Splash Mountain, Big Thunder.
Wishes is still a must as well as Fantasmic and Illuminations. The parades are more of a once a trip thing than every night like it once was.
We also go to Universal. They have larger thrill rides (bigger coasters) that older teens love. Revenge of the Mummy is another favorite. Sea World is also a must do.
Hard Rock Cafe and Margerettaville are popular stops while at the Universal Parks.
Hope this helps a little.
Penny