Once we can travel again...

I would stick with Spain. Unlike most people, I wasn't a fan of Lisbon, although the Aquarium was so good I went twice.

I would do Barcelona, Madrid, & Seville. Your message doesn't say how many days you will be gone, but I wouldn't want to go to the airport in the middle of a relatively short trip. I loved Lisbon (and all the places we visited in Portugal), and I loved Spain. I would do each country as separate trips, unless I had at least two months.

I would go with the first option. It's not so easy to tack on Portugal and Spain as many would think, there are historically little ground connections between the two countries. Your only realistic options would be to fly direct to Lisboa from Madrid or take a night train from Madrid to Lisboa. Best to save Portugal for another time and see the three main highlights of Spain.

Thanks everyone for your thoughts! Keep them coming.

We really do need to know how much time you have.

13 days is the plan

For 13 days (12 nights):

Fly in to Barcelona
Barcelona (5 nights) - day trip to Montserrat and/or Girona
AVE High Speed Train to
Madrid (3 nights) - day trip to Toledo and/or Segovia
AVE High Speed Train to
Cordoba (1 night)
AVE High Speed Train to
Sevilla (3 nights)
Fly out of Sevilla

Easy Peasy... as they say 😉

How many nights on the ground? Any time planned for jetlag arrival? Any time planned for a night near the airport for departure the next day?

I did the RS Heart of Portugal in 12 Days, followed by the Best of Spain in 14 days last summer.

I'd spent a week in Lisbon in 2011. I'd also been to Barcelona twice before, Madrid once and Seville once before.

I did 3 intra-Europe flights for those RS tours: Amsterdam to Lisbon, Porto to Barcelona and Seville to Amsterdam on TAP, Ryanair and Transavia respectively. (Before anyone asks, I flew into and out of Amsterdam because I have Delta flight privileges and AMS is my favorite European hub.)

If you only have 13 nights, your plan for a 3-city trip including Lisbon is doable if you fly. But I think that's really too little time for 3 cities and would recommend only 2 cities to see or learn much about them.

If you stick to Spain and include Barcelona, Madrid and Seville, the fast AVE trains with no train changes between them are faster than flying.

It's about 2.5 hours between Madrid and Seville.

It's about 3 hours between Barcelona and Madrid.

The longest AVE ride is 5.5 hours between Seville and Barcelona.

Now for a couple of links on this RS website that might help with your decision-making.

Explore Europe Portugal

Explore Europe Spain

Each of the 4 cities you list is unique and worthy of time and attention. It's very difficult to choose one over another. My personal choices would be in this order: Seville, Barcelona, Lisbon, Madrid.

Have fun planning and deciding over the next 12-18 months.

Due to the relatively short length of your trip, my suggestion would be to focus on Spain this time as there's lots to see there and you should have no trouble finding things to do for 13 days. Does the time frame you mentioned include travel days? I thought that Granada was fantastic, and visiting the Alhambra and seeing a Flamenco show were highlights on my trip.

One of the reasons I recommend Spain is because travel from Spain to Lisbon will use the better part of a full day. If using a night train, you may not get a good sleep so you may not feel like doing much on your arrival day. IMHO, it would be better to leave Portugal for another trip and spend more time there and see the country in more detail. I really enjoyed my time in Porto and while there you could perhaps take some short trips up the Douro River valley.

I cannot improve on Carlos's time allocations for the 3 key cities (and I like Cordoba better than Madrid if you set aside Madrid's art museums), but I'd prefer to have at least one extra night in each of those cities; I spent even longer than that in all except Madrid, plus extra days for side-trips. If you end up traveling in mid- to late-fall, I'd consider concentrating on Andalucia for reasons of weather, because it tends to be miserably hot in the summer.

This has all been so helpful! Thanks for all of the great comments and feedback!

I think sticking to a single country is probably the best solution. There is SO much to see in Spain and a very diverse culture from N to S. I have heard so much about Lisbon and the fun vibe. Also, there’s not option for us to fly out of Seville (unless we want multiple layovers) so we would have to navigate back to Madrid for the flight home. Not a big deal just a factor

Yes, for many origins Barcelona and Madrid seem to be the only affordable Spanish gateway cities. It would have cost me about an extra $500 to fly into Seville or Malaga rather than Madrid last year.

I am actually going to buck the trend and say for 13 days, take the highlights of 3 main cities (Barcelona, Madrid and Lisbon).....save Seville when you have time to go back and do the Andalusia area of Spain on its own. If you see Seville now, I am worried you won't return for Granada, with the Alhambra, Cordoba, white hill towns or Malaga. In the future, spend 2 weeks on the cities I have mentioned. You can do it by flying in and out from Malaga.
Though it is true that Lisbon is a different country, there are easy flights from Madrid. Start in Barcelona and keep heading West. Leave from Lisbon. Not sure why you don't want to fly from Madrid to Lisbon.