Train from Paris or Multi city flights

I would book a multi-city flight in terms for flying into one city and home from another. But other intra-European connections are probably cheaper to book on separate tickets with budget airlines; see www.skyscanner.com.

Paris-Lisbon is not a very good route by train. It takes at least 18 hours - 5 hours from Paris to Hendaye by TGV and then an overnight train from that border town (or from San Sebastian) to Coimbra or Lisbon.

Book your intra- Europe flights separately. Using budget airline they are very inexpensive. Especially Lisbon to Paris. I flew round trip last year for $84. Stockholm will be more expensive but still your best bet. You could try doing a multi city trip on Skyscanner or similar search engine then compare.
And, as the others poster said, a train to Paris is not the way to go.

I also like to use Google Flights to check on intra-European flights. I've been looking at one-ways from Amsterdam (sometimes cheaper than flying from Paris, often more nonstop flights) to Lisbon, Porto to Barcelona and Seville to Amsterdam for back-to-back Rick Steves Portugal and Spain tours next year.

Since I tend to arrive in Europe early before the tours and leave a bit late, I find the Dates option useful to see how prices change on dates and adjust accordingly.

This past summer I flew RT Seattle - Amsterdam on Delta. Then I did multi-city KLM to Stockholm from Amsterdam and back to Amsterdam from Bergen. I always allow plenty of time between flights and before and after tours. Full disclosure, that means a night or 2. Fortunately, I'm able to do that.

So click here to go to Google Flights and explore. You can see your schedule options and whether you search multi-city or separate trip, the flights will be on separate airlines with separate tickets. I just did a test for some dates in January. Paris to Lisbon, Lisbon to Stockholm, Stockholm to Paris. The total for the dates I picked was $200 or less. All flights were nonstop on different days about a week apart. All tickets were separate. There were 3 different airlines. Lower prices might be found by flying on different days than the ones I chose.

Thanks so much...I’ll check out google flights. Yes Amsterdam is a great hub. I didn’t realize they had more direct flights so I will consider that. I like to fly Kim.

It is no longer true that two-segment overseas flights are always more expensive. You should price what you want to see if there is really a premium. And the "remoteness" of Portugal, as well as your widely separated destinations suggests that the city changes will be tedious. (I have been to Portugal twice recently, and even Madrid and Milan are "far" away.)

coastalgardener, you will get better advice if you add your home city to your profile. For example, if you have United in your home airport, that's almost like having Lufthansa or TAP. And I've had great luck with two-segment Lufthansa flights, even a United code-share from the NYC area over the Atlantic.