all of them. Epcot was the shortest day of the bunch, but my 6 year old still talks about making her own car on the test track ride and my 9 year old is into science, inventing strange crap, etc. So we might be a little different.
One thing I would suggest if you are staying on property is to think about doing the meal plan. I was skeptical going into it that we would use it, but it turns out that it worked really well for us.