I have been a member for 2 years. There have been several times that I have required parts from the dealership, and my membership has more than paid for itself in the dealer discount. They say 10% at Park Place, but it has been as much as 40% on some parts. Of course parts are cheaper from other places, but I only have Saturday's and don't do well at planning ahead. The North Texas chapter is pretty active and has activities like steam cleaning and technical sessions at shops. The forum doesn't have as thorough of information as Mercedesshop (just my opinion) but I have found some good information there.
88 BMW E32 735i (make it go away)
95 Volvo 960 "Inga" (valve problems)
95 Nissan Maxima (the indestructible)
89 Ford Ranger XLT (ugliest truck in the South)