i have good sam club. I wisely signed up for that before i took my 7 thousand mile treck from michigan to cali and back. It's about 100 bucks for a year, which is far cheaper than calling a wrecker just one time.
I did call good sam for a tow truck about 1 am in san fransico when the bus broke down. I was told there weren't any tow trucks available until after 8 am and i should call back then. I spent the next couple hours wrenching on teh bus till i got her going and didn't need the tow truck afterall.
This is my only expierence with them. Though I didn't get the result I wanted, I will renew my good sam club for next year. It's just too good of a deal to pass up. I've had two flat tires since i had my good sam, but i didn't call either time. Once i went to the tire place and had purchased a new-used tire. The second time i just changed the tire myself at home in the driveway.
They also will bring you some fuel if you run out, or give you a jump start if needed. (if you have a diesel, chances are you will need a jump start with the fuel they bring you!)
Quis custodiet ipsos custodes (who will watch the watchmen?)