I met a guy last week with a CLK 430. Pretty car, but he was more enamored with mine. Primarily because of reputation for quality and additional room for rear seat passengers.
I have never found the seats, front or rear, in my car to be all that comfortable. In most MB's for that matter. Especially the SL's. I guess it depends on the individual characteristics of the person. I am 6'3'' 200+ lbs. If you wanted to put me in the back seat of a CLK for more than a ride down the street, I'd pass. If I were still a 10 year old, I'd be elated just to ride in a convertible MB.