We may not have time for both (traveling by bus/train) in late May - which would be better?
It really depends on your interests. If you’re into wine, definitely the Douro. It’s also much more picturesque.
If wine isn’t your thing and you are into history, Evora might be better.
While I like them both, if I had only had time for one, it would likely be the Douro. Btw - it might be getting pretty hot in Evora by that time.
I would agree with kathrynjs conclusion while noting that Alentejo also has much to offer the wine tourist. I can highly recommend Fita Preta, Esporao and Cartuxa all quite near Evora.
This is just what I needed to know - thank you!