We usually rent a car to save time and money. Two cars in your case. We usually hit
Walmart on the first day to load up on breakfast, snacks, water, and pop. We take frozen water bottles with us in a backpack to keep the pop cold. The savings on drinks alone pays for the car rental

. You can self-park for free at the Disney resorts and at the parks with the resort printout. If you want to go somewhere other than the parks to eat at night it’s nice to have the car. If you forget something or someone gets sick you’ll be happy you have a car. Disney World parks are spread out so you can either drive between parks or take the buses. The buses can take up to an hour to get you between parks.