I flew into Madrid from Chicago, and out of Madrid to Miami on Iberia. I spent some time acclimating and sightseeing on both ends of the trip (museums, 1/2 hour train to Toledo ... cathedral, etc.). I took a train from Madrid to Pamplona (~3 1/2 hours RENFE), and a bus from Pamplona to SJPP (~1 3/4 hours ALSA). I took the train from Santiago to Madrid since I did not prebook the return flight to Madrid (RENFE ~5 hours). The train was very comfortable, and I got to see a little of the countryside. I had both the RENFE, and ALSA apps on my phone. The RENFE app was a little funky when creating an account. I cannot remember the details, but it had a convoluted way of entering credit card info. Several of my travel companions had issues. I think we finally created their accounts in a browser, and then they were successful in booking tickets in the app. Who knows maybe it was user error, but we went in circles for almost 30 minutes before going online. I would suggest creating you account online at home. Having the app allowed us to book tickets, solidify our schedules, and skip the lines at the terminal. Trains can fill up and you may end up waiting at the station for the next available train.