Just a couple of quick suggestions
1) pack two pair of shoes/sneakers/footwear for each person. We have found that alternating each day allows for the shoes to airout/dry out/ mold back to original position. You will do lots of walking (we average about 8-10 miles/day) and nobody wants sore feet!!
2) have some groceries (particulary water and other drinks delivered to your resort) You will save a ton of money (case of water delivered 12 dollars for 32 bottles, WDW price 3.50/bottle). We generally have 4 cases of water delivered and probably leave behind about a half case from the 4 of us and we still buy some water in the parks as there is just so much you actually want to carry around on hot days.
3) like someone already posted it is near impossible to do everything in one trip! Plan, Plan, and Compromise as needed, but make sure each person gets at least one of their "must do's/priority rides". This will keep everyone a bit happier!
I know this does not answer your question on best parks but these will help you enjoy the parks better and longer before exhaustion sets in.
For us, our group consists of Me52, DW51, DS29 DIL 28 we rank the parks in the following order: MK, HS, EP, AK