When we did an overnight in Douro Valley we stayed in the town Peso da Regua at the Original Douro Hotel, it’s a pretty new hotel (opened last year) and it’s a beautifully renovated old building.
In Lisbon we stayed at the Torel Palace, another relatively new place and it was another exceptional hotel. We would most definitely stay there again.
What I would not recommend would be the full Douro river cruise from Regua to Porto, we did it, and it was way too long, once you get past the main vineyards in the region is gets boring and starts to drag on.
Now I want to head back over and spend more than just a couple of weeks!