We always do the 2 parks in the same day. We usually allow 2 days total though so that we can go back and redo our favorites on the 2nd day. But, this is how we do it.
We start the day out at IOA. We go to Seuss landing which is on the right when you come in, do all of those attractions, then cross back over and to go do Spiderman and Storm Force. I don't like coasters that go upside down so I don't do Hulk, but we usually take a few mins to watch the ride. It is fun just to watch people on it. After we are done there, we go to Toon Lagoon and ride Dudley and Popeye, then head over to Jurassic park to, as my 7 year old says "to scan the dinosaur eggs". My husband likes to ride the Jurassic park ride while I'm in the discovery center with the kids. Then we go ride my twins favorite coaster "The flying unicorn" then we head back over to Seuss landing and usually have lunch at Circus McGurkus because my kids love to eat there, then we head over to Universal Studios for the afternoon.
There we do Jimmy Neutron first, then make a long stop at the Mummy where my kids watch the Mummy cartoon while my husband and I take turns riding it over and over (depending on how long the line is). Then we ride Jaws because my daughter loves saying "that was a BAD shark!!!" in her cute little voice.
We then do MIB, BTTF, and ET. We spend a considerable amount of the afternoon over by Barney's playground, the Curious George place and the Woody Woodpecker coaster, but I have preschoolers so that's why.
Attractions that I think can be skipped if you are short on time are Twister and Earthquake. I didn't think either one was that good.
We like to end our day with dinner at Margaritaville. That's one choice that everyone in my family loves.
You should also check out
www.universalorlando.com for maps and attraction info. Hope you have a great trip!!!
