I've visited cobblestone a number of times. They have always done a pretty good job cleaning my car. Service is not overly friendly, but they are pretty good. I like their waiting area, both inside and outside, the seats are very comfy. I also love that they call you over speaker, that way in the hot months you can stay indoors while your car is getting the VIP service.
My only complain is that their reward system uses your license plate number to track your points, 2 out of 3 times the attendant enters the wrong license plate number. So make sure, if you want to rake in some rewards, to ensure your license plate number is correct on your receipt. By doing so you can get some detail service fot free!