My fiance and I usually only do it one day and honestly its only taken us a little more than half day. We go from park opening and leave around 5 depending. Keep in mind we do skip out the kid stuff, shows and rides we generally don't care about. It's expensive for us for the park to park plus the cab from Disney Property to US/IOA though. We are planning on doing this again in June. This is what we've done in the past and what we are planning on doing this time. We will be going with friends this time so it may take us longer to also accommodate what they want to do so we may use the full day but if you are mainly concerned with seeing HP than you will def see both HP parks and more.
US is our first stop and we'll get there pretty much at opening. Our first stop there is Diagon Alley, with Gringotts as the first ride. We walk around and get some Ice Cream from Florean Fortescue’s Ice-Cream Parlour (def recommend!). This usually only takes us about less than an hour. The first time we ever went Gringotts took us 2 1/2 hours but that was because it first opened. Now it's been taking us 20 mins or less and there is a single rider line.
Next we'll do MIB because that also has a short line. We haven't waited longer than 25 mins for it. Also I think there is a single rider line.
Next maybe we'll do Simpsons. It isn't a priority but again we've never waited longer than 20 mins for it.
We'll skip everything else on that side and make our way on the next side and probably skip rip ride rockit. We've only ever seen it with a 60 min plus wait and even the single rider line was like 30 mins. Plus the ride gave me a headache so I would skip it if I can.
Next would be Transformers maybe ( I say maybe because we recently went to US Hollywood with the same friends and it seems like the ride is pretty much the same?) If we do go it will be single rider which we've seen as 15-25 mins.
Then we do the Mummy because we love it. We would probably do standby which we've seen anywhere from 10-15 minutes and then possibly go on one more time with single rider which can be a walk on.
Next we would take the Hogwarts Express to IAO. We've only used it once but we waited about 20 minutes for it.
We would take a break at Hogsmeade and get some lunch and beer.
We'll do Dragon's Challenge which we've seen usually at 20 minutes and Forbidden Journey which we usually wait about 25 min. They also have a single rider.
Next Jurassic Park maybe (also because the ride is the same at hollywood but also its never a long wait).
Possibly Reign of Kong if by some miracle we see it at less than 20 minutes. I heard its a glorified version of the Kong 360 section of the studio tour in hollywood so meh?
Spider Man we've seen around 35 minutes and less so we'll do that.
Doctor Doom's Fear Fall because that has always been a walk on for us.
We are going to try to do Hulk but I haven't been since they refurbished it so I'm not sure what they weight time would be.
We're probably going to skip Jimmy Fallon because i heard its kind of crappy and non of us really watch his show #justiceforconan
Sorry for the long post. Keep in mind we've usually done the highlights of each park and still had time after but maybe it's just us being really lucky. What works for us may not work for you but this is our experience. Either way you should have more than enough time for each Wizarding World.
