Take the 500 bus from Aliados (sit up top in the very front in the huge window) and take it to Foz (the beach area) and eat at Tavi and then walk the beach. Take the wooden tram back to town. Eat a "Frenchie" sandwich at Cafe Santiago, drink Port wine at night at a touristic cafe right along Douro. Stare at the tile art inside Sao Bento train station. Visit the Porto Guitarra string shop and look at fantastic Portuguese made string instruments and ask Tico to demo some of them for you or if you are lucky some local folk might pop in and sit and play for a while. Eat nata and coffee in a completely traditional looking cafe and stand at the bar to eat and drink it. Go to Lado B and eat "the best chocolate cake in the world." Go to Foz and eat at Pizza Hut sitting on outside patio with a world class ocean view. Google the best piri piri chicken and go and eat it with locals. Visit the FC Porto soccer stadium and museum. Schedule a tour of Casa da Musica and experience what it is like playing some instruments they give you in that beautiful music hall. Eat french toast at Majestic Cafe. Visit Serralves Contemporary Museum and pay extra to walk in the "tree tops boardwalk. Then walk downhill and tour the Tram Museum. Walk around the campus of the University of Fernando Pessoa while reading his poems
Take a TukTuk tour and let someone show you the big picture of Porto etc etc etc
Best city anywhere!