We were disappointed today in Porto that we couldn’t get in to any of the port house tours, and I started looking online yesterday. Would recommend that as soon as you know you’d like to do this, you should find the house’s website and make your reservation. You can’t just walk across the river as described in the RS book and find a place.
We were in Porto at the end of April, and it was crazy busy. Long lines for the Harry Potter bookstore (which we didn't find that amazing). There is a pretty interesting stock exchange building (which isn't and never was what we consider stock exchange). We went there mid morning and secured tickets for the afternoon. It is described in the RS guide.
There are wine/port tasting places elsewhere in Porto. See the RS guide for info. We actually tasted when we were in the Douro (2.5 days) and only did formal tasting at 2 places, otherwise we stopped at the ones with views and had or shared a glass, being mindful of driving. So, when we got to Porto, we just walked on both sides of the river taking in the views. If you have time, perhaps you can take the train into the Douro and do some tasting near Pinhao that you can walk to. If you just stop for a glass and not a formal tour, you will typically be accommodated without an appointment and often will get some tasting info from the staff.
In a lot of ways, the beauty of Porto is just walking around. We did the Rick Steves walking tour, and also some routes suggested by our BnB. No one should ever miss the Sao Bento Train Station!
@jules m
We were in Porto in early May!
We gave up on the bookstore because of the very long line and took the Spanish language tour of the Stock Exchange building because the English language tours were sold out.
Strongly recommend it and the Sao Bento Station interior.