We just did this two weeks ago with National. Our flight landed around 12:30 pm, we used the Emerald Aisle service, drove through torrential downpours, hit some road contruction on I-4 about 10 miles from Disney, dropped the car at the Car Care Center in Disney World, they shuttled us to the Coronado Springs, we checked in, hit the pool, and still made our 6:30 pm reservation at the Maya Grill! All for about $39.00. It was my impression, though, that if you have a later afternoon arrival, traffic could get pretty bad out of the Tampa area.