I am going to Porto with my family for 3-5 days (two adults, and 12 and 16 y.o. daughters). We like to walk, sit in cafes, walk on the beach and swim and bike and are interested in a trip to the douro. also are interested in the old town but don't necessarily feel we have to stay there if we can be close to the water. We will likely have a car. Where would you recommend staying in Porto?