We did both parks in one day even though we had 2 days. It was a weekday during the 2nd week of November which is the off season. If you go in the off season, you'll definitely be able to do it. We stayed at the Hard Rock so we had the option to use our room keys for front of the line access, but never had to use it, because the lines never got longer than 10 minutes. Get to the parks 30 minutes before they open. Get your tickets and a map. I'd go to Universal 1st. Go directly to the ET ride, then Men in Black. Then work your way over to Twister which opens 1/2 hour after the park opens. The Jaws ride doesn't open until 1 hour after the park opens. After Twister, head for Jaws and maybe squeeze Earthquake in on the way. Do Back to the Future and Terminator 2 whenever you get a chance. These are the big rides. You'll be done before lunch. Then head for IOA. If any of the lines will be long they will probably be Spiderman and the Hulk. The rest were very easy to get on without waiting. Hope your experience was as good as ours. Have fun.