I agree with the PP, for IOA is shaped like a donut (so it's one direction or another). Although, I am like you, because I must have a plan. I see you're staying onsite, which is a great choice. You will receive Universal Express and Early Park Admission to IOA!
So, get up early and get to the park by 8am, and head right to HP and the Forbidden Journey (this does not accept Universal Express). After that you can knock off the Wanda shop, Olivander's (which may have a long(er) line by then and also does not have Express). While you are at the WWoHP, hop on the Flight of the Hippogriff and Dragon Challenge (both DO offer Express). It should be about 10am. I would head down to Seuss Landing (all rides have Express). Start off a Cat in the Hat, then head to One Fish, Two Fish, Red Fish, Blue Fish. Caro-Suess-el is next, and then the High in the Sky Seuss Trolley Train Ride. It should be almost 12:00, so head to The Eighth Voyage of Sinbad show.
Your next stop will be WWoHP for lunch at Three Broomsticks. Please note that this may be very crowded.
After you finish with lunch, let your food digest a bit and explore the Village of Hogsmede at WWoHP. Then head over to the Jurassic Park River Adventure. You may also find the Jurassic Park Discovery Center really neat. If you have young ones, they will enjoy Pteradon Flyers (this is a pain to ride though and is the only ride outside of WWoHP to not offer Express). Now, skip Toon Lagoon (you will return at the end of the day) and head to Marvel Super Hero Island. This is where you can ride the Amazing Adventures of Spider. If you are a real adrenaline seeker, ride the Incredible Hulk, and then Dr. Doom's Fearfall. After that, head right to Storm Force (we love this ride)! Finally, it is time for my favorite part of IOA: Toon Lagoon (so you actuarially have to got back up an island). Start off with Dudley Do-Right's Falls, and then top your day off with Popeye and Bluto's Barges. If you have little ones, let them spend some time afterward at Me-Ship: The Olive.
TIP: Spend a night at Universal CityWalk. There are some great restaurants (like Hard Rock Cafe and Emeril's) and some neat shops.