[fhofstra]

Thanks for the replies.
Yesterday I put in a replacement starter/solenoid assy (Autozone Duralast), and the engine has started properly, with no starting problems. Guess I will never know exactly what it was, since all the potential bad eggs get replaced in one basket, but I'm satisfied that starting is normal. Since the problem had gotten pretty solid the last few days, every time the engine was warm, I'm pretty sure this one is fixed -- half a dozen hot starts since install; every one of them good.
Next stop - radiator replacement, but that's a new thread.