Actually, your imposed itinerary is doing you some favors! First, it's actually a good strategy in general to go to a park that will close early for a party, as many people will avoid it, and you might find lower traffic during the day than would be normal for that time of year. (Bad news, it's probably a pretty high traffic time anyway, so you might not feel much benefit.)
And sure, it's absolutely worth hitting a park in the morning, leaving mid-day, and coming back later. It's a go-to strategy for many people; crowds are highest mid-day, so you just skip them and do your park-ing at the best times.
Now, proposed itinerary: This almost counts as a "first trip to WDW," so my advice would skew more towards doing things "thoroughly" and enjoyably rather than a plan that blows through the "headlines" for someone who has been often before. This means not just focusing on how many rides you do, or even the most popular rides, but also on "being there": taking time to ooh and aah at all the "Imagineering" that sets WDW apart from a Six Flags: explore Pandora, run around Tom Sawyer's Island, marvel at the Moroccan tiles or Japanese architecture. If Disney World had never built a single ride, it would still be worth going there just to walk around these other worlds (worth a very different price, of course). Don't miss the "attraction" of simply being there.
It sounds like you're there four days (i.e., four full days that you could spend "in park," not counting travel days)? Then I would advise prioritizing one park per day. If you were to extend your trip, then you could start talking about repeating parks, but unless you're planning another trip in the next few years, I wouldn't want to skip a park. (If you could see another trip in your future in the next few years, you could "save something" for then, for instance if they haven't watched any Star Wars media yet.) You could
maybe consider park-hopping, but we didn't on our first trip and I'm glad. Each park has plenty to occupy a day. In fact, you'll have to make peace with the fact that you won't do everything in four days; rather than break your neck trying, just try to be strategic about doing the things that matter most to your family (even if they're not the ones people talk about the most).
I'm not sure there needs to be a lot of careful strategizing to which park goes on which day.
Undercover Tourist has a
very elaborate crowd calendar with a learning curve (note, the green checkmark next to a park for a given day doesn't mean "this is the best park on this day"; it means, "if you have to choose which day to go to this park, and you're choosing between two days that have the same crowd level, this is the day to choose"). I'm not sure what arcane considerations go into its calculations, and you might take it with a grain of salt. But here are some other considerations:
- Thursday might be the lowest traffic day of the trip, as it's "not the weekend" or even a Friday
- Before you take anybody else's advice about which parks are "half day" parks, consider your own priorities. For instance, I could gladly spend all day in Galaxy's Edge, but if your kids aren't into Star Wars and too short for Aerosmith, you might have less to do there.
—Oh, wait, I just realized I might be misunderstanding. The two younger kids are 8, and haven't been since they were 2—but there are two older kids... and they
have been more recently? That might change the equation. But I'd still do one day per park.
