Universal and IOA have a lot to offer, for thrill seekers and otherwise.
Summary:
There are excellent shows at Universal in addition to some excellent attractions related to favorite films. Newest additions that you probably haven't seen yet are Men in Black, T2:3-D, Shrek 4-D, Jimmy Neutron, and The Revenge of the Mummy (if going May 21 or later). Includes updated versions of Horror Makeup Show, Beetlejuice's Graveyard Revue, and the Ghostbusters Show.
Fun stuff!
IOA is more of the thrill ride park out of the two...though even those who do not like thrill rides enjoy Amazing Adventures of Spiderman, the water rides like Popeyes, and Jurassic Park, and be sure to see the Mystical Fountain -- the talking fountain.
Anyway, I'll give the list for Universal. I'm sure others can help with IOA better than I....I spent almost all my time at Universal.

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Universal Studios
Jimmy Nuetron: Simulator that has taken the place of the Hanna Barbara ride. Those not a fan of today's Nick Toons may not care for the ride.
Shrek 4-D: Put on your 3-D glasses, and watch Donkey and Shrek save Princess Fiona once again from Lord Farquad. Includes some special effects and movements, despite being in auditorium seating.
Twister: You are basically watching as a twister forms in front of you, and destroys a Drive-In Movie Theatre. Neat if you are into how they do special effects, but some people claim it is a bit lame. Don't bother if there is a long wait, IMO.
Extreme Ghostbusters Show: My favorite show at Universal. Beetlejuice is in New York, and causing trouble. Ghostbusters have come to save the day...but BJ has different ideas... A fun 15-minute street show.
Street Breakz: Another short street show featuring some humor, and lots of breakdancing. Beware that they may look for volunteers at one point of the show.
Revenge of the Mummy (opening May 21): Dark ride with coaster elements. They call it a "Psychological thrill ride" due to some of peoples' biggest fears being included, like fear of bugs, etc. Awesome ride, that doesn't always need to be ridden by thrill-ride-seekers alone (My mom can't stand rollercoasters, but loves this ride).
Blues Brothers: Fan of the Blues Brothers movie? You should enjoy the show. Enjoy Mable, Jake, and Elwood (and don't remember saxophone player's name) as they perform classic songs. Lively and entertaining!
Beetlejuice's Graveyard Revue: The "Original Grateful Dead" (consisting of Wolfman, Dracula, Frankenstein, and his Bride...alongside back-ups Hip and Hop) perform some of the most well-known songs, from Bon Jovi's "One Wild Night," and Donna Summer's "Hot Stuff," to Ricky Martin's "Livin la vida loca." Hysterical show, especially due to Beetlejuice. Rated PG-13.
Earthquake: Suffer through long preshows (while, it's neat for some, like myself, it can be overly boring and drawn out for others) before you get to experience this attraction. You are in a subway when an earthquake hits.
Jaws: We all know of the Great White Shark that devoured the poor islanders at Amity. You are on a boat tour when you encounter a giant toothed demon of a mechanical shark. Oh no!
Men in Black: Alien Attack: You are going in for MIB Training, to see if you are the "Best of the Best." This ride is interactive, where you get to shoot aliens, and see if you earn your own black suit!
Back to the Future: Very rough simulator where you chase after Biff who stole one of Doc Brown's time traveling DeLoreans. Travel through the past, as well as the future, in this adventure. Classic Universal!!!
Animal Planet Live: Ultra cheesy, and fairly predictable, but for first-time viewers, it can nevertheless be somewhat entertaining. Nice when you want to take a break in the day.
ET: Dark ride based on the lovable extra terrestrial known as ET. Coolest part is flying over the city, otherwise it is more geared to the youngsters.
Horror Makeup Show: Like the Graveyard Revue, it has a PG-13 rating. Enjoy learning some tricks of the trade when it comes to makeup used in classic horror films, in the midst of lots of humor. **Volunteer Warning** Should NOT be missed!!
T2:3-D: Another 3-D Show based on Terminator 2. A combination of 3-D screens, and live actors.