I do think a week was too long. I think 4 days would have been more than plenty of time, with one of them being the Douro Valley tour..
My husband found a good craft beer place not too far from the river, so when we would got too thirsty we would head over there or find a place to buy a water and/ or a Porto tonic. Problem is then in 20 minutes I have to pee, so that means finding another restaurant to but another drink so I can use the bathroom. Rinse Repeat. It get tiresome and expensive. And time consuming because the service there is so slow! Things close during afternoon, which means waiting around for places to reopen.
One day to do walking tour. On this day we did a 6 bridges tour. This was one of out favorite things. The only caveat is that the young sales women told us to walk down the stairs to the river. The kept going and going and going. My knees were in extreme pain. (Already unhappy from hills in Santiago de Compostela, where I discovered my knees didn't like going down hills.). While at the river, we had to use a restroom so we ordered the worst 19euro Porto Tonic we have had yet compared to countless others. The waitress broke a large bill for us. When she gave us our change in the little bucket , she shorted us 50 cents.
One day for the Gaia wine district across the river. We took the monorail back to the bridge and walked across the bridge, so that we could ride the over priced funicular up the mountainside. My knees thanked me. That same evening, we saw an authentic fado show. It was great. Didn't understand one word but loved it. It gives new meaning to the tshirt we bought last year which shows a sardine singing fado. :D
The museum of port of whatever it was called was a waste of time. We had to wait an hour because the close down in the middle of the day.
We did the obligatory Douro Valley wine tour. Our guide was great. The scenery was beautiful. We only went to 2 small quintas. The first gave us samples of 3 wines. We went to go buy a bottle of dry white for Porto tonics and I saw others had olive oil tastes. I asked at the counter if I could taste it. They had only one but it was good so I bought a bottle of that too. The second quinta was 2 samples of wine. (not good to us. I don't even think there was a port, so we were thankful we got one when we did), also a sample of 2 olive oils. Again, we were not impressed and so thankful to have purchased the bottle at the first stop. This quinta also gave a tour of the old style olive oil production. Very interesting.
One day we took a daytrip to Aveiro. I wish I would have just taken the train out there as I originally wanted rather than the daytrip because while it was nice, we had only 10-15 minutes in the town and 20 minutes in another. Not enough to do anything really other than speed-shop the only open souvenir shop and use the water closet. I really would have liked to do the tour of the salt flats but it was only offered in English at 11:00 & 3:00. IIRC. The train would have put us there about 10:30 IIRC but I didn't know how to get from the station to the flats, so we did the safe thing and opted for the tour. That same day we toured the castle.
We took the trolley out to Foz to see the beach.