The best ways to travel around the region is by train, or by boat (I went up to Pocinho by train and back down by kayak). When in Pinhao, check out the train station, and its tiles panels. http://youtube.com/watch?v=b6hDoEk2bZE
While you're in the Douro Valley, you have to at least go to a vineyard, and taste the wine that this valley is so famous for. You can pretty much just go to any of them without an appointment, provided they are open. As you drive along the main road by the river, you'll see sign directing you to the various vineyards in the area. Just be careful on the narrow, winding roads. Especially after the Port!