My strategy so far has been to look for places with service managers named Art.
I highly recommend GM Exclusive in Vista CA
. They haven't seen my Solstice yet, but will now that it's not under warranty. Art has done excellent work on my Rendezvous, Alero, Sunfire over the years as well as many other vehicles for extended family members. They do quality work, charges match the estimates, work is almost always done when they say it will be done. And most importantly, they have never scratched, abused or broken other things - unlike the typical dealer experience. Art is the owner, is there every day and is gives good advice. (- I think they do warranty work as well, it was just more convenient to have the Solstice serviced closer to work.)
All warranty work on my Solstice was done at Richardson GMC (formerly Greiners) in Poway CA. They have replaced a turbo and performed major tranny repair in addition to the miscellaneous stuff. Always good work and Art is great to deal with. (the other service manager is good also)
I'm not easy to please and don't generally walk away from dealerships happy.
These two places have been the exceptions.