I would take sturdy fruit that will hold up in a backpack- apples, oranges.......
Definitely bring a water bottle- i'd imagine water for a family of 4 gets $$$ at Disney
Of course, eat a good breakfast like eggs- and that way you can enjoy the parks without getting too hungry before a nice dinner.

not the advice you were looking for- but I highly recommend the universal park "The 7 islands of adventure." each island has its own theme- like there is dr.suess land where they even sell green eggs and ham! And in comic book land, if you walk under the cardboard cut out looking cloud, it rains on you. It is really fun!