Hi. I've used Thrifty a couple times, so can help you here a bit.
A few suggestions about them.
DO NOT call them months ahead of time for a rate. It will sound ridiculous ($340 a week, e.g.) Don't know why, but their computer doesn't think about discount rates until about 2 months before the date you are booking.
DO call them a week or 2 days or some short amount before your trip, and you MAY find that they're the cheapest game in town. (Yes, Virginia, even cheaper than Alamo!)
They are quite good, actually. One of the closest places to the airport among the off airport places.
One suggestion, if you can afford it, rent at least an intermediate. All of their economy/compacts are Dodge Neons. And, I don't know about you, but I hate those cars. Reasons: 1. 3-speed automatic, so very (a) noisy and (b) lousy gas mileage. 2. Not very comfortable, even compared to its competitor the Ford Escort/Focus.
Hope this helps!
Oh, the office is just north of the airport on S. Semoran Blvd. 2nd traffic light n of airport I think.
Regards,
Joe Hurley