Is train travel feasible for this kind of itinerary? I'm wondering what all we can do via train, and what would require a flight. We have 26 days, plus or minus, and would like to fly into Madrid, train to Seville and do day tours from there, a train then to Valencia, and then onto Barcelona. Thanks.
We did 17 days all by train:
Madrid, Cordoba, Granada, Seville, Toledo then we flew out from Madrid.
It was fun and easy to do all this by train.
We loved Cordoba. Every night we walked along the bridge where lots of people were hanging out and we heard great buskers playing music and watched the moon rise and watched the birds moving about in the river below. Very romantic.
Yes, it's feasible. Train from Sevilla to Valencia would be almost five hours but otherwise it's pretty easy.
If you could fly to Sevilla and start there, it might be easier in terms of train travel, Sevilla to Madrid to Valencia to Barcelona.
My wife and I just got back from nearly a month in Spain including the RS 14-day tour starting in Barcelona and ending in Sevilla. A few things we learned about trains: AVE is the standard high-speed train; Avlo is one of several budget high-speed trains. We had tickets on the latter from Madrid Atocha to Barcelona Sants and ended up being charged €30 per bag as we boarded because our bags were over 55 cm high. This differs from the standard Renfe bag size limit.
You cannot get wifi on Avlo trains unless you have a Spanish phone number. (Frustratingly, the verification system dropdown menus for wifi access includes prefixes for non-Spanish phone numbers, but the system doesn't accept them.) The Renfe wifi is called "PlayRenfe" and is easy to access by using your ticket number.
Later in the trip we went from Córdoba to Palencia by AVE train, which involved a transfer between Madrid Atocha and Madrid Chambertin. We are over 65 so we qualified for an assistance service from Renfe called Atendo. You can supposedly sign up for it when you buy tickets online but the option wasn't there when I did so. There is an app for it but that did not work for me from the US. I sent various emails (after researching where to email them from the US) and ended up going to the customer service office at Atocha earlier in our trip to verify that we were in the system. It worked out, as we were met as we got off the train at Atocha and escorted to the Cercanias train station, where we took the local train to the Chamartin station, using our Renfe tickets. We had a 15-minute walk to reach the high speed train area of that station.
The Renfe website is notoriously difficult to use and it may take several attempts to get your tickets ordered. Get tickets as far in advance as you can to get lower prices.
Definitely doable, and I'd even say recommended. As others have noted, Sevilla-Madrid-Valencia-Barcelona is likely to offer you more options since more trains run to/from Madrid, but your itinerary would let you ride the once-daily train that takes you directly from Sevilla to Valencia. It's called the "Torre Oro," and while it's slow, it takes you through some gorgeous landscapes that you wouldn't see as much of on the higher-speed routes. I've not lived here so long that scenic train travel has stopped being a part of the appeal of travel in Spain!
In addition to IA Prof's good train advice, I'll add that you can always bring your own food and drink on board, so it's easy to pack a picnic and make a nice day of it. (Iryo, another Renfe alternative, also has a first-class option with full meal service - not usually something I spring for, but recently it happened to be just about 10 € more for a trip from Cordoba back to Barcelona, and having a cooked dinner with wine while rolling through Andalusia was a real treat.) Renfe sometimes (often, if you listen to locals griping about it) has delays, so I'd keep your travel days loosely scheduled and enjoy the journey.