Yeah, that's the most busy time to come, but at least you'll have your magic key.
Hit the parks in the morning. Sunscreen is a must, especially for you overseas tourists. You smother it all over, and 1 hour after you enter the park you're sweating bullets. It's sticky, sweaty, 90 degrees outside, but you've got a plan. IOA in the morning, then go back to your hotel room in the afternoon for lunch and the pool. Ahhhhh, recharge. Now hit IOA as the sun is going down for the night rides as everyone else files out. You'll see the tired leaving the park and you'll be ready to hit all the rides with your magic key. And don't forget, the Express pass machines run out at about 2pm, so you can keep going thru the express pass lines. I think this is the secret that has not been talked about. Think about it everyone. Express pass machines run out around 2pm for major rides. Hotel guests can keep going thru the lines. You visit the hotel pool, recharge, then come back to IOA at 4pm. You go thru the express pass lines and get on fast because most of the people waiting are hotel guests. Regular people have already used their express passes and the machines don't give out any more passes. Hotel guests can keep going thru these lines all afternoon.
It will work, just be sure to put on the sunscreen. Wouldn't want you to burn up.