Thank you gentlemen for your comments.....
Update: I took it to the dealer yesterday and had the service manager drive the car up to about 95. I also drove another 98 C230 with about the same mileage. It was interesting that the comparison car appeared to dance around even more than mine. I had just checked my tire pressure, and adjusted the wheel bearings in the front of mine. His comment was that my car handled pretty much as they all do, and after driving the other one, I believe he (and the many that have commented here) are correct that the sensitivity is characteristic to this chassis. I believe I can feel the difference between the compliance of the suspension and the movement of the car itself when the wheel is held firm, particularly in a cross wind situation.
I believe this car is simply "nervous" at high speed, wind or not, with the OEM wheel/tire combination.
Anyway.....in my search for stability, I had also discovered that the front wheel bearing adjusting nuts were both about 10-15 degrees loose, resulting in a very noticeable wheel/bearing movement. I initially tightened both sides to finger tight, and it drove with improved stability. Then I took a look at the MB procedure, courtesy of the dealer. It calls for .01-.02 MM axial play in the rotor/hub, with respect to the inner race, as measured by a dial indicator. I happen to have a metric dial indicator, and in checking, was actually quite close on my adjustment by feel. If you do the math, this is about 4 to 8 ten thousandths of endplay on the bearing set
(about a half thousandth), a very small measurement indeed. I noticed a distinctly more stable behavior after setting them to the correct clearance.
In any event, I do realize it is not an S class. On the other hand, for those of you guys that have corroborated this sensitivity, it seems as though a 16 or 17 inch low profile tire has improved the stability in every case. Thanks to all for the very complete commentary.....I have pretty much concluded that if the alignment is right on, the bearings set correctly, and a good set of tires at the right pressure, this phenomenon is characteristic, though minimal if everything is right on. Don't think it is going to act any different until the tires are changed. I think I will try a low profile wheel/tire combination.
Thanks again for all the comments.
98 C230 ( In search of an S class at 90 plus