You're getting a lot of advice, and normally I wouldn't muddy it up further, but... :lol:
I would pay close attention to the entertainment schedule for the time you're intending to go. With things as slow as they are projected to be, there are lots of entertainment cutbacks on the way.
For example... There has been rumor that Illuminations might go to only a few nights a week. I don't think it'll happen, but let's use it as an example.
That would mean that you, along with everyone else that has planned well for the trip, would have to be at Epcot one of those three days that week to see it. To me, that would mean that Epcot will be much busier those three days of the week. That's when you have to ask yourself: Might it make more sense to go to a park that you know won't be crowded that day because there's no night time show, then hop to Epcot in time to see Illuminations? Is the extra cost justified by the much shorter lines you'll spend the day in?
Or... Let's say they're only showing Spectromagic two nights while you'll be there, and you've planned to spend one of your days at the MK in order to see it. But it rains that whole night so it's canceled. And since you don't have park hoppers, the only other night it's being shown, you've already got planned to be in a different park that day.
The park hopper option gives you the flexibility to make on-the-fly changes as needs arise. I couldn't imagine visiting without it.