I have used Dollar as much as all the other on airport agencies put together. Good prices (if you surf for codes) and good service. As tmeyer said, join the Fast Lane to cut down on line time.
I have also never been asked for a gas receipt although I gas up pretty close to drop off. From 417 I go south on Boggy Creek Rd about a mile or so. There is a convienence store with gas. Then back to the north on Boggy Creek right into the airport.