Little late to this reply so probably no longer needed for you, but I rented from Thrifty at SFO about a half dozen times this past year for work and I always had good service. My car was already already ready for me as Blue Chip member and I even went to the window in the garage (as blue chip member) and was able to get different car easily. The garage window never had a line or maybe like one person.
Checking in when returning car was easy as well, longest wait was a couple cars ahead of me when the rep would walk around your car and give you a receipt but no more than 5 minutes, very reasonable.
I've always had good luck with Thrifty and they are usually always the cheapest deal I can find. I kind of feel bad I found a cheaper deal with Hertz for a recent trip since I like thrifty so much!