I suggest 4 places to go, and a great place to stay

Pinhao, an interesting town on the Douro Valley

Casa de Mateus, this famous estate is near Vila Real

Quinta do Panascal, vineyard and port cellar , 12 minutes from Pinhao

Lamego, a beautiful church and spectacular gardens with its grand stairway

Stay at Casa Dos Barros Villa, Sabrosa not far from Pinhao

see the following posts for details.

Another way to explore is take a tour like this, Wine tours