Anyone planning to visit the Douro should emphatically leave enough time (at least a day, preferably two) to travel its length by train. It's one of the great railway journeys of the world. You can go from Porto right up to the Spanish border - it used to go to Salamanca but the Spanish closed their end of it. But you will get an unparalleled view of the river and the vineyards on the way. You can stop off at Pinhao for some excellent food, with a short walk to some important producers. But Porto itself is so much worth the visit with much to see/visit, plus Villa Nova de Gaia a quick stagger over the bridge for Port sampling purposes. Probably my number one area.
Alsace is great. And to be honest, most Australian wine-growing areas are good to visit these days. I'm leaving so many out which I have enjoyed, but of places I have never been, the mention of Georgia has just moved it up several rungs. South Africa would be great if I could get my act together.