Sara's apartment gets my highest recommendation. The location is great, close to the river and a ton of stuff, but in a city that has a lot of construction, it is above all else, quiet and peaceful. Yet still a five-minute walk to the river and close to the beach. Even more than that, Sara went above and beyond for my wife and me when we had some travel woes. She is one of the best hosts that I've had, which can make all the difference in the world. If you're going to Porto, you'd have a hard time finding a better place to stay.