We are taking Rick Steve's tour finishing in Porto at the end of June and we have another 10 days after that to see more. Should we see more of the Douro Valley or head to the Algarve area or do both?
The Douro Valley is amazing. Don't miss it. The Algarve is a beach area and frankly after going to beaches in Europe, the only place I really liked t he beaches was on Greek Islands.
The beaches in Florida or the Caribbean are better.
If you can, take a cruise on the Douro, we did a wonderful on for a week.
With 10 days you have time to do both. Portugal is a small country so you could take a couple days to explore points between.
The Algarve at the end of June will be very busy with pasty Northern Europeans such as myself seeking some sunshine.
I would try to see the Douro and the north of the country.
Douro
There is just so much to Porto than Faro
For those not familiar with the tour itinerary, it spends a day and night in the Douro Valley, followed by two nights in Porto: https://www.ricksteves.com/tours/spain-portugal/portugal.
Pat, I'd also consider Santiago de Compostela (Spain), though there's pretty much only one decent train connection or one direct bus per day, and you'd probably return the same way, if flying home from Portugal.