The only thing no park-to-park tickets will cause you to miss is the Hogwarts Express train.
Early entry at IOA - most people head to Hagrid's, and if you are not near the front of the pack they will probably tell you the line is 180 minutes when you get there. So maybe do the other EE rides like Velocicoaster, Flight of the Hippogriff, and Forbidden Journey, and try for Hagrid's when the wait time goes down later in the day. Lines for other rides should stay on the shorter side in the morning - I enjoy Jurassic river adventure, Kong, and Spiderman. I have been on Hulk, but like Velocicoaster so much better that I usually skip it these days. The other 2 water rides in Toon Lagoon will get you quite wet. I like the Seuss trolley ride, and that line gets very long too, so I try to do that in the morning.
US opens at 8 in Oct. If you want to ride Minions, do it first thing because that line gets crazy long also. Gringotts is very popular so I would ride it early. The single rider line is usually much faster if you don't want to wait but you miss the preshow. Men in Black has a SR line also which is almost always a walk-on. Mummy may be busy because it has been closed for refurbishment (also has a quick SR line). The line for Rip Ride Rockit was pretty low much of the time I was there. I wouldn't wait in a long line for Jimmy Fallon ride (it's cute) or Fast & Furious (unless you are interested in all the car stuff in the queue). Transformers is very similar to Spiderman, ET is a nice little ride, the Simpsons is also fun but makes some motion sick.
Walk over to VB for EE and ride the aqua coaster with no line, also Ike Moana and Honu.
Take time to enjoy the little things that happen as you walk around the parks. Concerts, performances, characters, the attention to detail in each section of IOA is interesting, as well as in the Harry Potter areas. The shrunken heads in Knockturn Alley sing and tell jokes, until someone waves a wand at them to make them stop. I enjoy listening to Kang & Kodo of the Twirl & Hurl but usually don't bother riding it.