Your choice so just do what you like:).
Want to save time over money? Choose a meal plan. As a frmr food and beverage intern for a major hotel chain, I can say with little calculation that Disney's food plans enriches it's bottom line by offering safe choices for the harried, the not quite sure, and those with deep pockets. It's a sales market so honestly decide on your priorities.
Concerned about what and how your family eats in general? Make your own snacks and sandwiches, store them in an insulated bag, and bring them with you. Want to step away from the all you can drink soda pop world? Provide each child with a water bottle, attached to their wrist or yours. Since ice is free, the occasional juice pack wont get too warm.
HTH.