OP's scenario is our situation every year. In my mind, the only reason to take that early flight is to go to a park!!
After we check in we head right to MK. We have to walk down Main Street and see the castle or the vacation hasn't started yet!! Then we go over to Toontown and say hello to Mickey. Next, we head back to Main Street to catch the parade (usually taking the train from Toontown to Frontierland and walking through Liberty Square to get a funnel cake to eat while we wait for the parade to start)
Then we hop to another park for dinner. This year it is MGM for a quickie dinner at the Pizza Planet, see the Osborne lights and hopefully catch the early Fantasmic (but we may be too tired at this point!)
Then the next day we are up early for a 8:00 AM at Crystal Palace and we finally ride the rides at MK...