Disney is full of fun thrill rides; they're just not "in-your-face" like other theme parks. Disney puts a story to each ride (makes them even better!). Here is a list and brief description/review of each "thrill ride" at Disney. I've also rated them based on thrill (or how thrilling they are to me; I'm a thrill-junkie). Here's my scale.
1 - Slightly Thrilling
2 - Moderately Thrilling
3 - Extremely Thrilling
Magic Kingdom
Space Mountain - 3 - There are two tracks: Alpha and Omega. Both are about the same in terms of thrill, if you ask me. The ride itself it pretty thrilling with drops (no inversions) and high speeds. The seats are low to the track making it even more thrilling and it is not a smooth ride by any means, as it is very bumpy and "jerky."
Splash Mountain - 2 - If you don't find drops thrilling, than this isn't really a thrill ride. It is a dark ride with a drop at the end. If you're like me and get nervous about drops, than you'll find this to be extremely thrilling. There are two mini-drops and one giant one. I like the story and find it to be very suspenseful, so get ready to get nervous!
Big Thunder Mountain Railroad - 1 - For little ones, this may be a 2 (then again, everything would be at least a 2 for them), but really is just speed. There aren't any drops. Even the speed, though, isn't that fast. Some wouldn't even call it a thrill ride, but I still find it enjoyable. A nice warm-up.
Epcot
Mission: Space (Orange Team) - 3 - Do not go on this one until an hour after eating or else there is a high likelihood, you'll throw up. This is really the only thrill ride at WDW I cannot stand. Between the small space and intense spinning, the ride makes me miserable. That being said, many enjoy it, but it is a physically demanding ride.
Test Track - 2 - Can't comment on the new one, but the old one was very "jerky" and moved extremely fast.
Sum of All Thrills - varies - This one is just like CyberSpace Mountain except it has much longer waits and is much shorter. You get to build your own roller coaster and everything, thus riders can create a less intense experience or an extremely intense experience. It is always a lot of fun but often experiences long waits and doesn't offer FASTPASS. Get there early (right after Soarin').
Disney's Hollywood Studios
Rock 'n' Roller Coaster - 3 - With this one, you can listen to Aerosmith music (good or not) while launching at 60 MPH into one of three inversions. It is unbelievably fun and beyond thrilling. The suspense as you wait continues to build and is well-worth it when you begin the ride. Throughout the darkened ride, you'll see some neon light and hear some music. It's an absolute riot!
The Twilight Zone Tower of Terror - 3 - Another extremely thrilling ride that is not for everyone. When you board your "elevator," you enter the Twilight Zone, go to the top floor, the windows lower, and you drop in a random sequence 6-8 times. Definitely take a look at your picture, for it is usually quite funny. There is little to hold on to, which makes it uncomfortable for some, so, again, use caution when riding.
Star Tours - 2 - A somewhat "jerky" ride that is rarely the same. Overall, it's a simulator that you share with maybe 40 or 50 other people, so that diminishes the real thrill level of the attraction. It's still thrilling and somewhat scary to small children with the loud noises, shaking, sudden movements, and such. I think it's an okay ride, though.
Disney's Animal Kingdom Theme Park
Expedition Everest - 3 - This is one of my absolute favorite rides at WDW between the amazing queue, attention to detail, and exhilarating ride. I really enjoy it because of the many drops (no inversions) and speed. It is purely an awesome ride.
Dinosaur - 2 - Employing sensory overload, Dinosaur can be more irritating than thrilling, but it still is a fun thrill. The level of speed and movement is high, but there are no drops or anything. In fact, the ride vehicle is rover that couldn't handle any of those. The ride is fun but just doesn't do it for me.
Primeval Whirl - 1 - Another one of my favorite attractions is this one because of the spinning and drops. If you pay attention to the story, you may find it actually quite funny. My family loves to ride it over and over again, because it is just that fun. In terms of thrill, it's not bad at all, but is very jerky, includes drop, and can be a bit fast at times.
As you can see, Disney has thrill rides and these are just some. Here are some mild but wild thrills that are fun for everyone.
Soarin' (somewhat)
Mission: Space (Green Team)
Toy Story Mania! (somewhat)
Mad Tea Party
Haunted Mansion (not really for youngsters)
Barnstormer
Maelstrom (just the end maybe)
Buzz Lightyear (somewhat)
CyberSpace Mountain at DisneyQuest
Humunga Kowabunga at Typhoon Lagoon
Summit Plummet at Blizzard Beach
So, there you have it. There are many thrills at Disney. I hope you have a great trip!