Nice that they leave the trucks open so you can load your bag. The only downside is you can't easily tell what model of car you're picking. Unlock the trunk, but leave the lid down.
Chai Odom
Use the Emerald Aisle and just walk right up to any car with a key in the door. You don't even need a reservation, they'll sort you out when you leave th parking ramp.
Andrew Murphy
Pretty much a cluster to return your car. Not sure it's worth it for the ease of check in.
Tracy Boarder
Accessed by choosing "Level 3" in the parking ramp elevators.