The WDW transportation system is for use by on-site Guests, and by any Guest with a park-hopping ticket.
Just in case you are also thinking of parkint at DTD and riding a bus to the parks in order to save the $9 a day parking fee - nope. There are no busses from DTD to the theme parks, and no busses from the theme parks to DTD, for the specific purpose of preventing folks from parking there to avoid the parking fee.
Paults is right, if you are going to eat at one of the WDW resorts, the best way is to drive directly to the resort. You will get a 3-hour parking pass, which is usually more than enough to have a nice meal and explore the resort a little before you leave. Parking directly at the resort will also save you 30 minutes or more of travel time between DTD and whatever resort you're eating at.