We stayed outside the tourist areas, high, away from the river. This had two advantages: we always began the day walking downhill, not up (and we walked down, or level, all day, and so we could use funicular, bus, or cab to get back); and we went to non-touristy, local, Portuguese restaurants. Nova Era was one. For 22 Euros, we had a very good meal, much more than we could eat: a half-bottle of good Douro red wine, 1.5L of water, chicken with fries and salad, and Brazilian steak with black beans, rices, and fries. Service was excellent, our waiter's English was quite good, the food was well cooked (my steak was nicely rare, and well-marinated). What is not to like.
I have one more general comment: at local restaurants, we have received *vast* amounts of food. We could have ordered a full order of the steak *OR* the chicken, with sides and wine and water, and have had enough to eat. The couple next to us did just that: split an entree. (They had desert, too.)
Now we know.