Of the places I've been in Europe, the country I'd most like to see again is Portugal. On my last visit, I did a pretty good job of covering a lot of the country (though I didn't manage to get down to The Algarve, unfortunately). We spent a lot of time in Lisbon, and made it out to Sintra (which is just as fabulous as you've heard), saw the old college town of Coimbra, and went up north to Porto. But what really made our visit to port wine country was venturing out into the Duoro Valley, itself. If you restrict your visit to the north to the city of Porto, only, you're really missing out!
To begin with, the scenery is gorgeous. We traveled from Porto by train to Pinhão, a small town along the Duoro River, which made a great jumping off point for visits to local wineries. The train is a great way to see the valley, because it runs alongside the river, pretty much. But driving's not a bad option, considering that you'll probably want to stop in at many of the wine lodges.
We took a really fantastic course--well, it was more of a tasting, actually--to learn how to pair wine with chocolate. I can't remember much about what I learned in that course (I may or may not have been drinking fortified wine all day), but I do remember that it was fun!
Another great way to see the valley is to take a short cruise on the river. We had an informative guide who gave us a lot of insight into the particular viticulture of the area. It was a great way to get some education about the unique characteristics of the Duoro Valley, and how it results in the unique characteristics of the wines that result. And, at the same time, we were seeing beautiful scenery throughout.
And, of course, because it was Portugal, the food was incredible. Of any of the places I've been in the world, I don't think I've ever had food that was so consistently phenomenal as I did in Portugal--and throughout the country. Each meal was more crushingly awesome than the next. And it's no different in the Douro.