Drive in Portugal with fear of heights?

Can't think of any I have suffer with the same problem.

If you stick to the areas you mentioned, you will be fine. The only potential problem area would be the Douro. But, in my very limited experience in that area, the roads are winding but there aren't any real cliffs to speak of. If you are concerned about that area, you can always take a tour or the train.

I recently drove through one of the more mountainous areas of Portugal. Even there, the highway was wide (and much better than most interstates in the U.S.) with no cliffs, hairpin turns, etc.

All that said, if you get off the beaten path, you can likely find roads like the ones you want to avoid. But, if you stick to areas you mention, you should be fine.

Going up north from Évora you won't get any cliffs or dangerous roads along the way. Even if you don't stick to highways (auto-estradas or IPs) and you choose to do a good part of the way through national roads (N-???) you'll be just fine. National roads take you closer to the sea and very near of great, yet less known places like Peniche, São Martinho do Porto, São Pedro de Moel, Nazaré, Figueira da Foz, Aveiro (my hometown), Espinho, etc. Even in the Douro region, there's little or no problems that you may come across. Yes, you'll find a lot of winding roads (on the N-type framework) as most of them were designed a long time ago on a particular landscape that, at the time, didn't allow anything else.

Don't know if you remember that the N-222 from Peso da Régua to Pinhão in the Douro Valley was voted the most beautiful road in the world. Not sure about the "most beautiful" but still, a wonderful place to visit. A lot of bends of course, but beautiful and safe. (http://www.dailymail.co.uk/travel/travel_news/article-3052472/The-world-s-best-road-voted-Portugal-s-wine-region.html)

There are a few scary roads in Portugal but they're a bit further north and some of them in the Serra da Estrela area.

Thanks so much for the helpful replies! It sounds like he will be fine driving - which is how we prefer to travel. One additional question - would it be feasible in early October to leave a few nights of our trip without hotel reservations so we have the flexibility once we arrive. Of course we would have reservations in Lisbon, Porto and the Duoro (if we overnight there rather than a day trip), so this would be in a smaller town. We did this in Croatia and Slovenia and we actually discovered things we wouldn't have otherwise.

Yes, I think you'll be fine! Just consider making a shortlist of a few hotels in potential stopping points.