I am very excited to be taking my kids to Universal for the first time (that they can remember). They will be 4 and 6 and both over 42 inches. My son (4) is a thrill ride lover and has already done his first looping coaster (Sooper Dooper Looper and Hershey Park). My daughter (6) liked Splash, Test Track and Big Thunder but didn't like Space (at Disneyland). My daughter loves most characters my son isn't likely to want to meet any even if it is someone he likes.
We are not staying on site and are doing 2 days here and 1 at Leogland - no Disney this trip.
We have not been with kids this age before. Any tips for making the trip extra fun for them?
Prioritize Minion Mayhem. It is low capacity and will have long lines most of the day. You can find times of the day when the Harry Potter rides will have relatively short waits. But Minion Mayhem has long waits almost all day.
We found a surprising amount of cool stuff at Universal. The kids did well on simulator rides. The Simpsons is slightly more intense than Minion Mayhem. From there, you can try out Transformers or Spider-man (if you only get to do one, choose Spider-man). Everyone also enjoyed Men in Black. ET is okay if the wait isn't long, but not worth waiting in a long line.
You can spend a lot of time just exploring the two HP lands. Diagon Alley is so immersive. Waits for the Hogwarts Express can be quite long. But there are pockets where the wait is relatively short. If you're lucky, you can time your park hopping around that. If the waits are too long, you are better off walking between parks.
Obviously, Seuss Landing is great for kids. Camp Jurassic is a cool playground.
Our experience was that Universal was a lot less crowded and easier to navigate than Disney World. We felt free to explore without having to run all over the place to make prescheduled FPs or beat the crowds. By afternoon, the parks were almost empty and this was in late June.
My biggest tip is just to slow down and explore. Universal is smaller than Disney World and much more compact. There's no FPs, no ADRs. You can relax and breathe easy. No need to rush.
We went to Olivanders and our oldest was chosen to participate. No real tips here except to try to be close to the front of the room. When we went in, I knew Josie would be chosen. There was only one other kid in the group which was mostly adults. So if at all possible, try to go in when there aren't going to be a lot of kids. I know, easier said than done on that one.