As a proud (and much poorer that originally) w140 owner, I can't say that the steering wheel is small; I'd say it's rather large... Is it possible that it had a steering wheel switched over from other model ? It's definitely bigger than the 92 Camaro, or 89 Volvo 740 GL steering wheel, and it's massive -- another reason why I like it so much, it looks great from the side view...
The door hand rest, I agree, but I have my left on the steering wheel, and right resting on the center console -- I drive with my left hand, while the right rest on the shifter. And I haven't been in more comfortable car yet. IMO it's far better than w210, but then again, I have a '92 S-class, that's before they cheapened the model in 1995.

__________________
2004 CL 500
1992 400 SE