Anywhere is a bit unspecific ;-).
Before I post a zillions list, this is what I usually did: step at the C office and have a chitchat with the counter. After some minutes and successful transfer on all family history of the counter clerk, I usually get the contact data of somebody renting me a plane for x days. Did this dozen of times and it always worked in CA (and not only there) immediately.
Best story: I was in San Diego for a fair and had three spare days to look at the countryside, before had to head back to SF bay area. Went to the airfield, found a nice Skyhawk by assistance of sweet little Nancy and rented it for the three days right away. When I was back, I met the owner and we spent a nice bottle of Sonoma wine at that evening. During the long chat he told me he was going to San Francisco and what do I have to say - he asked me to take the plane up, because he had to move all his stuff by car already. So, I did cancel the flight back and took the Skyhawk.