We like to take advantage of EMH, and we usually go during busy times of the year, so we like to use those extra hours. That means split days at all the parks.
MK late at night is grand,so we have one full day at MK, and several evenings there. Epcot is a day and a half for us. MGM, I could do one partial day and be relatively happy. Last trip we did a half day and an evening. AK used to be a 3/4 day park for us, but EE makes it worthy of a return, at least for a half day. It's also hard to fit the shows into one day. We saw Nemo the second visit.
Then again, we've also done shorter trips (3days) too. MK is a must, Epcot is a must. EE is a near must. MGM, I could skip and be at peace. DTD we see about every other trip. I've never made it to the water parks. I've been to Disneyquest once, though we did enjoy it.