You can do everything in one day with time management.
For IOA: Be there at opening, ride everything in Marvel, then it really doesn't matter. Just know what you want to do and when. Know what you want for lunch and plan it on the park route. Use Express passes for Spiderman, Hulk, or Dueling Dragons. Water rides should have shorter lines. JPRA is not that great, so it is low on the list. Every wait in Suess Landing should be under 30 minutes. Every island except Marvel empties out about one hour before closing.
For US: MIB/BTTF first. Work your way around to Jaws, Earthquake, Kong, Twister, T2, and ET. The Hitchcock and Horror Make-Up Show are excellent and not to be overlooked. Use Express passes for your favorite rides. If you like MIB, then use single rider line for that. That is probably the greatest time saver. The whole park empties about an hour before closing, so you can basically do what you want then.