suggestions for Porto- Lisbon by car

Hi Ellen, first I want to commend you on taking the time to write an organized well-written post.
With that said and because there is a direct train from Porto to Lisbon (3h 15m) I suggest going back to Lisbon and sleep in the Alfama neighborhood that is one of the four districts that makes up Lisbon’s old town. It has a village feel and is a good place to wander and listen to fado music at the mom & pop restaurants before going to bed each night.
Rick Steves 11th edition PT guidebook has three must-do self-guided walks that will introduce you to the best of Lisbon. I would take one each day. If you have time, go to Belém and tour the Monastery of Jerónimo.

Both options have merit. There is sufficient in Lisbon to keep you occupied, however, there is also much to see in Portugal - towns such as Coimbra, Tomar, Alcobaca, Batalha etc, although you would have to be selective with your limited timescale. I would opt for the driving option.

I´ll chime in agreement with Jennifer (I'm a big fan of driving for just the reasons that you have stated). You might want to add Braga and Guimares to you list. In fact, you might want to add another two weeks to your stay in Portugal!

It really depends on your interests. If you like smaller towns, I would suggest driving so you can see a few. Jennifer mentioned the places I also recommend. If bigger cities are more your preference, take the train and explore Lisbon.

Driving in Portugal is quite easy if you don’t try to drive in Lisbon. The toll roads are excellent and sparsely traveled (outside of Lisbon). The signage is good in the smaller areas even without gps.

Day trips by train from Lisbon would be very different than the things you can see by driving. Take a look at the places mentioned vs.train day trips from Lisbon to help you decide.

Depending on your time in interest I would recommend hiring a Rick Steves guide for the day to help you get around Lisbon. The city center is spread out among four neighborhoods so having a guide was really helpful. I emailed Christina Duarte who is listed on Rick’s website. Her husband Pedro was my guide, and was excellent!
Next time I am back, I plan to rent a car. The highways are great!

Spent two weeks in Portugal few months ago and I totally recommend car. It gives you so much flexibility to be in different places. Made a road trip myself and along the coast there is many small towns and sights to see. Flexibility of the car gives you lot of freedom and saves lots of headaches.

Following along as I am researching a possible trip to Portugal as well. Ellen, I would love the information about your hiking trips if you don't mind. Please feel free to message me if that's easier for you. Thank you!

For the Douro Valley, I suggest taking the train, it goes up on the north side of the river. Another option is to take a cruise. Many placed to visit vineyards.