Depends on the work you want done. Glover's Garage in Cumming is good, one of the guy's wives has (or had) an SLK320 with 300,000 miles on it - he knows the car.
What are you fighting with the car? Ever been to one of the Tech Days in Gainesville that the local group holds? That's where most of the work has been done on my car - while I fix sound systems nad other stuff, the guys have done my brakes and changed fluids, etc.