We will visit London and Paris for a few days prior to the RS Spain tour this fall & then spend a week in Portugal before flying back to US. Assume we take the Eurostar Train from London to Paris, but seeking travel recommendations from Paris to Barcelona, Seville to Porto and Porto to Lisbon. With the exception of Paris to Barcelona, it appears the train is optimal for travel between other sites, but appreciate recommendations. Given our tour group meets on the day we travel from Paris to Barcelona, we need to fly. However, there appears to be several airlines serving this route; is one more preferable than another?
The quickest rail routing from Seville-Santa Justa to Porto-Campanha takes 11 hours and requires 3 transfers (one of them quite short), so I'd certainly look into flights. Try skyscanner.com for that.
Trains from Porto to Lisbon take roughly 3 hours.
I like to use the Deutsche Bahn website for train schedules, though you won't be able to see fares or buy tickets for Spanish and Portuguese trains there.
Ryanair flies from Sevilla to Porto. That is optimal.
Airlines to Barcelona:
Joon and Easyjet from CDG
Transavia France from Orly
Vueling from both
I'd look at prices and schedules to see what fits best. Then I'd do a google search for reviews of Joon and Trasavia, if either of those is promising, because I've never heard of either before.