Knowing universal crowds, you could probably do both parks in half a day!:drevil:
Slightly off-topic, I know and I'm sorry, but I don't understand the logic of not rushing through either park if you don't have to.
Granted, at that time of year, mid-December, before the holiday crowds, UO/IOA might indeed be dead. On top of that, you have your hotel pass which will give you front-of-the-line privileges everywhere. But it also gives you the opportunity to look around and savor little details that might get lost on a busier day.
Don't boot me off the board
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, to me UO/IOA is pretty much an expendable side trip. If time or budget finds it incoveneient, I don't have to go up the road. But if I were going, and had the free rein that their hotel pass gives you, I'd soak in the parks for all their worth.
Incidentally, I'd suggest UO for the first day, get some rest and then hit IOA's roller coasters the next day. I like UO, but there seems to me like there's more show than motion at UO. Even flight simulators seem to shake me up less than their coasters or Spiderman does. And many of UO's more enjoyable attractions don't move as fast as a coaster does (I'm thinking Men in Black, ET). You have enjoyable stationary attractions like Shrek, Twister, T3D, the Monster Makeup Show. The only flight simulator that tends to knock me over is BTTF, and that's mainly because I always wind up banging my head on the back of it. You're probably going to be sleep deprived the day you get there, antsy, unused to the weather...UO, while not exactly relaxing, seems to me to be less physically taxing. So I'd say either hit UO your first day, IOA the next morning, and then back to UO if you need to catch something you miss or re-do an attraction, OR just go to both parks both days, take in mostly shows and stationary attractions the first day, then go nuts with their "E-ticket" rides the 2nd. day.