5 days in France after Paris then on to Lisbon

If you drive (you'd need a rental car), Dordogne is actually a good idea. You can take a train from Paris to Bordeaux, rent a car there, and on the way back from Dordogne there are flights from Bordeaux to Lisbon.

Conversely, the Loire Valley does not have any airports in the first place - you'd have to go to Orly or Nantes, so I would not consider it to be the best option.

Brittany is OK if you can head to Nantes for the flight.

Alsace could work if there are flights from Basel to Lisbon, but not otherwise.

Yes thank you, getting to Lisbon must be part of the equation, was even thinking we might have to go back to Paris for that purpose.

I think Alsace is a good choice. You’re probably closer to Frankfurt than Paris from there, which might be a desirable/easier option for flights to Lisbon. The Loire is lovely, but imo you need a car. I suppose you could say the same for Alsace, but it didn’t seem quite as necessary was I had researched it.

We just did three nights in the Loire and it was fabulous! Relaxed, beautiful setting, incredible chateaus, and everything is cheaper! It was such a nice change from Paris! However, you will have to return to Paris for a flight to Lisbon. It would be very simple with a 2 hr TGV from Tours to Paris. Although I'm not sure what other options there are for transportation besides flying from Paris. Have you reviewed rome2rio for some options?

thank you all so much for the great advice. To think that we can spend 10 days in France and not have to make tough choices about where not to go illustrates how many amazing places there are to see and visit. I think that we will do Dordogne and have to forgo the lovely Loire and Alsace region and save them for another trip. I wanted to use this time to appreciate an area without too much rush and after the city life of Paris Dordogne seems perfect. The plan is to take the train to Bordeaux, rent a car and drive to Sarlat area. I booked a place near Vitrec and will use this as a base to explore the area for 5 days before returning to Bordeaux to return car and fly to Lisbon. I will now do a deep dive on the forum about the Sarlat area. Any suggestions do's and dont's appreciated! Towns to avoid or must sees. Our goal is to explore at a leisurely pace after 5 days in big city Paris. We will do a canoe river excursion, hiking and markets.
Also, would it be worth it to spend a day or two in Bordeaux ( at the expense of Dordogne) on way back? Surprisingly I found nothing on Bordeaux in Rick Steves France book!
Again Merci
Antonio

Check the Toulouse airport, too. The Dordogne is halfway between Bordeaux and Toulouse. Choose whichever has the most flights to Portugal per day or per week.

My recent direct flight home to my hometown in France from Rome was cancelled recently and the next flight wasn't for five days. So go where there are plenty of flights.

Excellent point. In fact, upon further inspection, there appears to be many more flights from Toulouse, and I would hate to get stranded! Looks relatively same distance to get to Sarlat

The best thing to do in my opinion would be to pick up the car in Bordeaux (closer to Paris) and return it at Toulouse airport.

Although it doesn't fit your needs directly, for the record I thought I'd mention that Aéroport Tours Val de Loire has flights to Porto.

If you were interested in Normandie or Bretagne, the Rennes Bretagne Aéroport has flights to both Lisbon and Porto.