Thanks for the replies!

Certainly I have considered keeping my aged W124 -- it only has about 190K miles (!) and overall it is in excellent shape. Still, there is about $7K worth of maintenance due over the next few years, and I doubt it will get better with time.

I'm not wedded to the W124 though -- what about newer models of the E and C classes? The S probably is too large and expensive, even well used. I've not kept up with these newer models...