You have received a lot of helpful replies, and about the only thing I can add is that I just took my family to Universal Studios on Sunday. So, just some thoughts, maybe with a mix of buyer's remorse.
How old are your kids? You said just one day at Universal, right?
We went down for my daughter's gymnastics meet, which was Friday, and made it an extended Orlando trip. We went to Disney a couple of years ago, so wanted to do the other stuff this time around. This is a regular meet on my daughter's gym's schedule, so I imagine we'll be back in 2 or 3 years. I was pretty tight on the budget and time, and probably tried to pack too much into a few days - SeaWorld on Saturday, Universal Studios/Islands of Adventure on Sunday, and ended up doing Atlantica on Monday. Of those, the only one I regret is Atlantica, as it is pretty expensive for what it is. Overall, I think we did try to do too much.
Specific to Universal, we got the 2-park 1 day park hopper passes. We happened to get them through the gymnastics meet at a discount, so unfortunately, I don't know how to get you a hookup there. The hotel we stayed at (Best Western Orlando Convention Center) did have a kiosk selling discounted tickets, but I didn't look at the Universal prices since I already had them. I didn't get the impression the discounts were spectacular (maybe better than AAA, though!). If you are a Costco member, you could check their travel deals - they have Universal, but it looks like it's going to be a hotel/park bundle.
We were there on a Sunday, so I don't know how that influences the busyness of the park. We got there when the park opened at 9 am, and went straight to Islands of Adventure. We did the Hulk ride first, and that had maybe a 15 minute wait. Overall, the lines weren't too bad - we rode most of the rides. If you are going for the rides (and your kids are over 54"), I don't think you'll be able to ride every ride in both Universal and Islands of Adventure in one day. We did end up skipping the Harry Potter rides (Islands of Adventure) and Minion Mayhem (Universal Studios) because of the wait times. Our longest wait was the Transformers 3D ride, which was about an hour (but worth the wait, in our opinion). Most wait times were 15 minutes or less. If you want some pointers on which rides are worth it/less worth it, I'd be glad to inject my opinion there. If I were to focus on just one park, that would be a tough call - both had some fun rides and shows.
Plan on at least 20 minutes of walking from your parking spot to the entry of your park of choice. It's a long hike from the parking ramps (we parked in the Jaws section, which I believe is the furthest away), through security, and through CityWalk. Security was a bit of a mess, mostly due to people being rude.
The food prices at Universal are insane (at the same level of insane as any of the Orlando theme parks) - figure around $15 per person per meal for crappy food. Their food plan is confusing, too. We did buy a couple of refillable souvenir cups (about $15 per cup, a little less if you buy several). You can bring a backpack with snacks and up to 2 liters of water. Of course, then you'll need somebody to hold all your stuff while you ride rides. Some rides allow for you to bring a bag on, but it's confusing as to which ones will until you get there.
They have the Mardi Gras parade going on now, which was fun for the kids. As a father of two girls (ages 11 and 9), I'm not so sure I'm excited about my girls being excited about getting beads at Mardi Gras... lol!
Oh, and sunscreen - Universal's main park isn't especially shady. Islands of Adventure has some more shade.
Travis Rassat
Vector Cycle Works Noblesville, IN
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