well, John, I read your specs for coffee mugs with interest, as I also have difficulty finding just the perfect one. I went and studied the 3-4 that I use most, and I note that they DO conform to your general design, though all have minor deviations. I note that they all are 'nearly' vertical inside, and 3 or the 4 have relatively thin rims, though two are a bit taller than you prefer. There is a bit of a flared rim to two of them, but it is mostly decorative, and not enough to be a problem.
   Interestingly, the one which comes closest to your specs was bought from a potter at the Kansas State Fair in Hutchinson about 1973! I would use it more, but it is one of the taller ones and holds more coffee than I 'usually' drink...that is, I usually brew 4 'cups', which makes 2 medium 'mugs', and my most used mug is just the right capacity.
   If I were to improve on it, I would make a thinner, more comfortable curve to the handle, as I like to slip 3 fingers thru it, with one outside/below....and I'd like that 4th finger to help support the mug from the outside (kind of a double-curve). I bought IT at a 2nd hand store, though it was originally also a stoneware craft item. I have a couple of smaller cups that are 'ok', but I use them only when I am making smaller amounts.

I guess the handle shape is my biggest complaint....I want to go to a potter and sit there while they make a handle precisely to fit my grip!........

(Oh, I will use plastic...the insulated type...when driving, and have built myself custom holders in my van for almost any shape of beverage container.)