Our guides were Porto locals so knew the town and its history inside out and backwards. We did a custom bike tour so got to see a bit more than usual which was all well worth it. If you are looking for a hotel recommendation, I can't recommend the Hospes Infante Sagres enough. It was one of the cooler old school hotels I've ever seen. When not on your bike, be sure the check out the nightlife along with its food and restaurants on both sides of the Douro River. We didn't get around to trying to some of the local port tastings (all of the major brands have huge cellars on the north side of the river) be had enough elsewhere. Also, there is a new shopping center on the north side of the river that we briefly biked past that is apparently also well worth seeing if you are into that sort of thing.