Thanks for all the suggestions. Over the years, many (not all!) of the items mentioned have been regularly maintained or replaced. Early on, the dealer did much of the more difficult work, but I have used two very good local Benz specialists in the last 15 years. I have a set of factory manuals and still do everything that I can do myself.

Some comments and updates:
1. The front struts (Bilsteins) are on order; I didn't order new mounts, but I will today along with the rear shocks.
2. Caliper brake hoses are probably original and I will replace them.
3. I'll definitely do the differential soon.
4. The flex discs were replaced years ago, but are probably worn out again.
5. Cooling hoses and drive belt are pretty new.
6. I agree with "a time to let go", but my wife and I like the car and feel like it is part of the family, so until something catastrophic happens, we'll continue motoring along............
7. My biggest unknown is the engine. The plugs actually look pretty good. No fouling. I just cleaned the engine and I hope to see the leaks a bit better. I could do the valve cover and maybe the valve seals myself. Ditto for the upper front cover. However, it might be wise to get my independent to do all of this while replacing the head gasket and inspect the rest. It's tough though, because I'm cheap.

Again, thanks to all!
Brent