We did it and had a great day!!! We came in a day early to get a discount last October, so we spent our first full day doing this for fun. It was a spur of the moment thing. We actually hit 5 parks- because we did EPCOT twice! If you can arrange it, I would suggest going either from HS to EPCOT, or EPCOT to HS, it is a short walk (or boat ride- if you happen to walk out of one when the boat is getting to the dock and there is no wait)- that can really save you some transportation time.
This is what we did:
DHS-- FP+ Toy Story Mania, Spent a lot of time in One Man's Dream because DD (9) is very interested in the history of Walt right now and she had never been in there, and we knew it would likely close with the DHS expansion; FP+ Star Tours . We had a TOT FP+, but DD didn't want to ride it. Walked to EPCOT.
EPCOT- Duffy's last day (waited 70 minutes in line to see him); F&W for lunch. It was a Saturday, so EPCOT was packed and we were ready to leave after hitting a few of the food booths. Bus to AK.
AK --- Safari, Walk around and see animals because DD would not do EE single rider (she needs her Dad next to her to be brave enough for that ride); See Lion King Show. Bus to EPCOT.
EPCOT- Return for ADR at San Angel. Ride Boat in Mexico. Ride Spaceship Earth on the way out. Monorail to MK.
MK- ELP, fireworks, shop. We may have ridden something, I can't remember. Mostly we were there just for the purpose of 4 parks in a day and our next day was a full MK day, so I can't remember if we even went past the hub that night.
We had a great time- it is so fun to be able to say we did 4 parks in a day! We had no must dos and no real plans other than seeing Duffy was a must. That is actually how the whole idea came up. DD's request for our extra day was to FP+ TSM because we usually only ride it once in a trip as the standby line is always too long. When we found out it was Duffy's last day, we knew we had to go see him because DD loves him. We had a dinner ADR at EPCOT, but it was so crowded that day (a F&W Saturday), that we wanted out of that park. Spending the afternoon there sounded miserable. AK was the recommended low crowd park, and we thought we might see some Florida friends on our later AK day, so we decided to head over there to do some things in case we didn't want to stay there on our actual AK day. The minute we made the decision to go to AK, we knew our new goal was a 4 park day and we had to get to MK before the end of the night!