Hi - I'll be in Madrid in late october and want to get a roundtrip ticket from Madrid to Sevilla for the weekend of Oct 27. We cant leave until around 10am Friday and want to return not too late in the evening on Sunday. The AVE looks to be cheaper, given our schedule, unless Im overlooking some great flight deal, but I understand you get a discount if you book in Spain at Renfe rather than online. BUT does the train fill up if you wait until the day before departure to buy the tickets ??? Appreciate any info.... thanks

Late October should not be a problem and flying will take much longer as you will have to get all the way to Barajas and then from the airport to Sevilla and back.

I would take Renfe.

The trains are certainly the best way of going from Madrid to Sevilla. The AVE trains are normally every hour, but are busiest around weekends, so may fill up on Fridays and Sundays. I've used the line twice and on both occasions had to travel in "preferente" (first) class because the "turista" (second) was full. The fares on RENFE's web site should be the same as those at stations, and the web site should tell you if trains are full.

cyntia,
I agree with lacalire and Geoff,

RENFE. Prices thru TIKNET should be the same, as Geoff says.
Once on Easter Monday, due to a snafu, we needed to purchase last minute Seville-Madrid tickets at the ticket counter right before departure. All tourist class seats on all trains were sold out, but we were able to find 2 seats in preferente for an additional 30 euros.

Hi-
Do you arrive in Madrid in the international airport? If so, there is a RENFE office to the left after you exit customs.
I was there last October and bought my tickets from Madrid to Sevilla as soon as we landed (for departure 3 days later).
However, if you MUST take a specific train, it is a bit of a risk to wait until the day before.