Let's start with Universal Studios:
Production Central
Jimmy Neutron: Most of the kids are familiar with the Nick characters from the ride especially the Rugrats, Dora, and SpongeBob. It is a fun 3 D silmulator ride with stationary seats for younger kids. When you exit the ride there is an interactive area where kids can send an email to friends, be the director of a cartoon, or control the sound effects of a cartoon. They can play a trivia game and, if they get enough correct answers, they win a round on an arcade game. SpongeBob also has a meet and greet in that area. You don't even have to go on the ride to enter the interactive area.
Shrek: Stationary seats are available but the best thing is the meet and greet with Shrek, Fiona, and (my favorite) Donkey. I can spend quite awhile just listening to Donkey interact with the kids.
Woody Woodpecker Kid Zone
Animal Planet Live is fun for kids to watch but the Barney show is every little kid's favorite. After exiting Barney, there is a play area where kids can make music, splash in the water, or draw on the walls. There is also a meet and greet with Barney.
Curious George is a wet and dry play area. Kids can squirt people with water cannons or run upstairs to dump buckets of water down. There are all sorts of water interactive areas. For those who want to stay dry, there is a Ball Factory where kids can shoot and throw nerf balls and plenty of climbing for the little ones. The balls are soft and safe whether you are throwing or getting hit.
Woody's Coaster is a kiddy coaster. ET is also a fun ride for the kids. Listen for ET to say your name at the end of the ride.
Fieval's Playland has tons of interactive elements and everything is at a mouse eye's view. There is also a slide where kids can take a two person water raft down.
World Expo
Kids love standing inside the giant coca cola bottle and getting fogged.
Now on to IoA:
Suess Landing
The whole land is built for kids, with even the fences, signs, and steps are built kidsize. One Fish Two Fish is like Dumbo but with water. Caro-suess-el is a whimsical caroussel full of Dr. Seuss characters. Cat in the Hat has some spinning but kids love this ride.
If I ran the Zoo is another interactive play area. Kids can crawl into holes, squirt water on a small island, and play tic tac toe. There are plenty of areas to climb and get some energy out.
If your youngest is at least 34 inches, another fun ride is the High in the Sky Seuss Trolley Train Ride! A trolley ride around Suess Landing starring the sneeches.
Other areas in Suess Landing: Toss a coin into the mouth of the fish in McElligot's Pool to receive a surprise. Sit on Horton's Egg outside the Cat, Hats, and Things gift shop. Walk through the street of the Lifted Lorax and listen to the Once-ler. Stop by Sneetch Beach and listen to the story of the Zax. Meet the Grinch, Cat and the Hat, and Thing 1 and 2.
Jurassic park
The Disovery center there is a mini-science center where every exhibit is based on dinosaurs. Kids can test their dinosaur knowledge, X-ray the inside of a dinosaur egg, have their DNA sampled to create a new dinosaur, search for bones in a rock, and can "Beasuar" by looking through virtual reality glasses in dinosaur models, or watch a dinosaur hatch in the nursery.
Camp Jurassic is a play area where kids can run through caves, squirt water, climb rope bridges, and go down slides. There is also a kids' ride called Pteranodon Flyers where adults can only ride if they are accompanied by a child.
Toon Lagoon
The Me Ship, The olive is a tri-level play area. There are stairs to climb, slides to go down, and a piano to play. They can squirt the people who are on the boats at Popeye and Bluto's Bilge Rats.
Marvel Super Hero Island
Storm Force Acceltron is a teaccup clone. This one makes me dizzy but kids love it. And there are characters who ride into Marvel several times a day for Meet and Greet.
Now all of these examples are for little kids. You can buy a 2 park ticket for only $10 more than a one park and park hop during the day.