Although there aren't any fireworks/light shows/parades at the moment, Universal is opening up some new shows in the studios this year that sound like they'll be great- one is a parade and the other is a nighttime show in the lagoon. If you're visiting during Spring Break I don't think these will have started yet.
What do your kids like to eat? Are there any themes (like Marvel, Harry Potter, Jurassic Park, etc.) that they would really enjoy? My personal favorite quick service restaurant is The Three Broomsticks in the Wizarding World. Mythos in the Lost Continent section of IOA is a favorite of many- it's a sit down restaurant but the prices are not outrageous. The themeing inside is incredible!!
The best rides in each park is definitely a matter of opinion! I think Harry Potter and the Forbidden Journey is the best of either of the parks, and I'm also a big fan of all the coasters (Hulk and Dragon Challenge in IOA, Rip Ride Rockit and Mummy in Studios). I also love the water rides at IOA and Men in Black at the Studios.. heck, there's just too many great rides to name!
Spring Break will most likely be crowded. You might consider buying Express Passes to bypass most of the lines. If you stay on-site, your room key will act as an unlimited Express Pass. However, Express Passes don't work on three rides in the resort- Harry Potter and the Forbidden Journey and Pteranodon Flyers in IOA and Rip Ride Rockit in the Studios.
