Despite all the bad hype and bad vibes I have used Payless for Disney trips numerous times and had no problems.
Payless is one of the few agencies that does reserve the right not to rent to you if you don't have collision insurance on a car you own back at home and decline their collision coverage. L&M and EZ are two others in that category that come to mine.
From Payless, turn right instead of left out of their lot, two quick lefts at the next light less than a mile gets you onto the Beach Line (528; fka Bee Line), then one 75 cent toll, then on to I-4 west (southwest) to Disney.
Coming back, follow signs carefully for I-4 East, then onto 528, get off 528 at exit 9 Tradeport, left and cross under, (nice cheap gas station right there to top off, then) get into middle lane (facing north), required right onto McCoy, Payless is on left about a mile down. (If you kept going, less than a mile is Semoran where left goes to Hertz and some more expensive gas stations and right enters the airport).
Disney hints:
http://members.aol.com/ajaynejr/disney.htm