Transfering from Madrid Airport to Seville on day of arrival an other travel questions.

The 11:50 should be fine, but of course serious delays could happen. Under normal circumstances say you land at 7 (common short delay), it takes 2 hours to get out of the airport, and one to get to the train station. That puts you there at 10 which is plenty early.

If you book the later train you have longer to wait, but more of a cushion in case of delay. Best case scenario you get to the station very early, put your bags in a locker, and have a few hours to wander around and see a bit of Madrid. I’d probably book the later one, but that’s out of an abundance of caution.

We did that--arrived Madrid at 6am and took a train to Sevilla. I was not at all comfortable about buying tickets in advance, and that trip was about 5 years ago. Now with the issues with the airlines, there is no question, I would not buy the ticket in advance. For our flight, we ended up getting in a bit early, and the airport was dead. We got a much earlier train than I would have expected. I believe we were at our Sevilla inn by 11am, maybe earlier.

Here are my suggestions. You could buy an advance ticket for one or two days after your flight and stay in Madrid or go to Toledo (you would have to take a 30 minute train ride back to Madrid to catch the train to Sevilla, which will also be at Atocha, no big deal).

Another idea, if you are visiting Cordoba (I sure would, its amazing), you could buy those tickets when you arrive at the Madrid airport. Cordoba is not as far and the tickets would be cheaper. Then after a fun time in Cordoba you can take the train to Sevilla. Cordoba is worth at least 2 nights, BTW.

Lastly, of course, you could just buy the ticket to Sevilla when you arrive at the airport, and not give it much thought. For us, had I purchased the tickets in advance, I would have saved 40-50 euro on both tickets. When we travel when we don't have a rental car, we don't take taxis, we either walk or take public transportation. I felt like these tickets purchased day of were a reasonable "splurge".

FYI, Madrid is one of the airports like London, Amsterdam which has had huge problems, of late. I understand there was a line out the door of the airport for the security screening, which or course you wouldn't need to do on arrival, but I would guess if the screening is that bad, there are other issues at that airport.

The Renfe site has descriptions for the various tickets. If semi-flexible refers to the ”Elige” ticket, it looks like you would pay 30% of the ticket price for a missed train.

https://www.renfe.com/es/en/viajar/prepara-tu-viaje/billetes-ave-y-largadistancia/todos-los-billetes.html

It is a risk vs reward situation. Determine what the cost difference is in an advance ticket vs one day of. My fumbling figures it to be 80-90 euro day of, vs 50 to 60 euro...so 30 euro per ticket. Risking the early train and missing means your out the 50-60, and have to pay 80-90 (unless the missed ticket has some value, or you can reschedule at the airport); getting there early means you sit for a few hours. Probably the safer, budget conscious choice is to take the later train, and if everything goes well, find a nice place for tapas and a drink to wait for the train. Bolder would be to wait and buy there, buying the early train is probably the riskiest, but that would require serious disruptions...but if the reward is a few more hours in Seville, or a comfortable arrival....then maybe worth the risk. There is no right answer.

Also, is it better to take a train or bus from Seville to Granada?

Check train and bus schedules and decide which one works best for your time frame.
Both are comfortable and convenient.
Do keep in mind that the train station is closer to the city center.
The bus station is at the outskirts of the city so you’ll need to take a city bus, or a taxi, to get to your accommodation.

We took the ALSA bus in/ out of Granada( years ago) and a taxi to our hotel.

I just checked ALSA.com and noted discounted tickets as low as €5/ person.
These discounted tickets are unrefundable & unchangeable.

Enjoy your time in beautiful Spain!

Check cost of flight from Madrid to Seville for travel 90 to 120 minutes after your Madrid arrival. Call this expense option A.
Option B is combined expense of travel from Madrid Airport to Train Station plus cost of train.
A - B = C
C should also consider benefit of traveling via same mode (plane) without needing to transfer form point A to B.

So wouldn't a flight from Madrid to Sevilla on presumably a different airline be just as risky as purchasing a train ticket in advance? If the first flight is delayed or cancelled and you miss the second flight, you are out the ticket cost.

The trains from the airport to final destination are priced together. The portion from the airport to Atocha is a couple euro, if that.

We prefer to stay with the same mode of transport and view it as being a less stressful travel day. We have done both modes of travel and now choose to fly through Madrid, or Barcelona, and onto "beginning" destination. A bit more efficient when booking on the same airline service. We live in Florida and find IBERIA meets our flight needs to destinations in Spain (we strive to stay off US carriers for international travel). Once we experienced a flight delay of 90 minutes, but were fine with being in the Madrid Airport and waiting on the solution.

Thank you all for your comments

I’d buy the later ticket at a fully flexible fare, and if I were early try to change. But I’d be guaranteed my seat on the later train.

And yes, if you have a long-distance (AVE/Alvin) train ticket the commuter (Cercanias) train from airport T4 to Atocha would be free. (Normally 2.50€, I think). Arriving at terminal. 1/3 taking the subway might be easier—though it would be a little more, and out of pocket.