As a 17 year old, I understand how Disney is becoming a bit worn out. I have started wanting to go to Universal more in search of thrills instead of dark rides. Which I find strange. Because I used to LOVE dark rides. So.. Here are some tips from a currently 17 yr old... Nothing unique or anything.. Just the attractions that should not be missed.
MK-
Not much to say about MK. Unless he really wants to go on a dark ride, I'd just avoid Fantasyland all together. What was once my favorite childhood land is now my least favorite land in the parks due to whining children, and long wait times for "boring" rides. Mickey's Philharmagic is the only worthy attraction. Maybe Little Mermaid, given that it is a very short wait for a pretty relaxing ride when y'all get tired. Spend time on the typical teenage-happy attractions like Splash, Thunder, and Space Mountain... Pirates of the Caribbean, The Haunted Mansion, Buzz Lightyear, Ect. Monsters Inc. Laugh Floor is a hit or miss depending on whether or not the guy has a sense of humor. Avoid quote on quote "dumb" things (In the words of teenagers) like Jungle Cruise, animatronic shows, Stitch, ect.
EPCOT-
Test Track and Mission: Space... Must do. SUM of All Thrills in Innoventions is also a really awesome must do. Especially if he's a thrill seeker. The rest of the park is just going to be kind of "meh" to him. Unless he finds the countries in World Showcase cool. When he starts complaining about his legs being tired, or it's too hot, go to Ellen's Energy Adventure or Circle of Life if you're in Future World, or The American Adventure if you're in World Showcase. Either way he can nap or relax. Everything in the park is hit or miss. Except Imagination. Stay as far away from Imagination as possible. If you are not on a budget... A fun thing to do might be to try different desserts at all the different countries!
Hollywood Studios-
Rockin Roller Coaster, Star Tours and Tower of Terror are always a win-win. Toy Story Mania is great too. Problem with this park is that those three are about it for great rides. The Great Movie Ride and Muppet Vision might be a hit or miss. He might find Indiana Jones Epic Stunt Spectacular pretty great. Nothing much else to do in the park now unless he's a Star Wars fanatic and wants to check out the Launch Bay.
Animal Kingdom-
DINOSAUR, Primeval Whirl, Expedition Everest, and Kilimanjaro Safaris, yes. Finding Nemo and Lion King are hit or miss. He may get a good kick out of It's Tough to be a Bug. That's a pretty intense show.
I don't know how many times he's been, or if he's a thrill seeker or not... But everything I've listed is everything I never miss because they are my favorites.