We recently travelled Barcelona (Passeig de Gracia) to Figueres return, also one way Granada Cordoba, Cordoba Ronda and Ronda San Roque (for Gibraltar). All trips were good except for the outbound Barcelona Figueres, we took an all stops local which pretty much was a stuffy subway car ride for over 2 hours. Our fault for not doing a better job on choosing our train. Also Passeig de Gracia station is under construction, platform was very hot and crowded, we probably would have done better boarding at Sants. The trip back was a semi-express, more comfortable cars and food/bev vending machines. Toilets were reasonably clean by railroad standards.
All the other trips were on Alteria equipment, comfortable and fast enough, although with stop for gauge adjustment at Antequerra to and from Cordoba. This seemed to take about 15 minutes. Scenery was interesting on all routes in Andalucia, especially into Ronda and down to San Roque. None of the trains were crowded except the outbound Barcelona Figueres.
We were Tourist (2nd) class.
We waited until arriving in Spain to get our tickets, and bought them (except for Barcelona - we bought those with no trouble at P de G station) at a Travel Agent (Viajes Ecuador) near our hotel in Granada. Not sure how their pricing compared to the RENFE website but the tickets seemed reasonable enough and it was an easy process.
Some differences in Spanish rail travel vs other parts of Europe, in Granada and Cordoba we lined up and were checked in airport style at the gate when boarding started, you then just find your seat and your ticket is not looked at again. But give yourself some extra time at the station before boarding as I think they shut off check in a few minutes ahead of departure, no last minute dash onto the platform and into the train as it pulls away! Also in Cordoba they do a luggage x-ray before you check in and go down to the platform but this didn't take long. Just be aware that at major stations it is a bit like boarding a plane. Ronda was traditional get on when the train pulls in. Also we had trouble seeing the car numbers when boarding, they seemed to be a little random, i.e car 10 was next to car 6 on one occasion. Station stops are very short, be ready to get on and off promptly.
Didn't check out food/bev on Andalucian trains, may have also been vending, not many people seemed to be consuming it. Trains were all on time, stations well marked, staff were helpful and competent, stations (except P de G) were pleasant and clean. This was a good way for us to get around in Andalucia.