It seems a lot of people prefer the parking structure but my wife and I usually opt for the Toy Story lot. With 2 kids, stroller, bag, lunch cooler, and jackets it's just easier for us to load/unload and maneuver via the bus rather than the tram and having to wait for the elevator in the structure. We tried it once and may have to again since we may have just had a bad day.
Where do you like to park??