Santiago de Compostela Airport is located about fifteen minutes from the center of the city. It is relatively small but has great facilities. At the entrance is a large self-service cafeteria and shops selling Galician products - cheese, wine, spirits and souvenirs. It is the only Galician airport offering intercontinental flights (to South America) as well as European destinations (Dublin, Rome. Paris, Liverpool, London...) and of course domestic flights to Barcelona, Seville, Madrid, Gran Canaria, Tenerife, Bilbao, and others. A taxi from the city center to the airport costs around 16 euros. If you prefer to go by bus, there is one that starts at Calle Doctor Teixeiro and also passes by the bus station, for 1.80 euros. The service begins at about 6 in the morning and runs almost until midnight. Iberia, Vueling, Clickair, Aerolineas Argentinas, Air Berlin and Ryanair are among the carriers that operate lines here.
I've used Ryanair a few times, most recently to fly from Valladolid to London Stansted Airport. It wasn't the unpleasant experience I was expecting it to be. But I did dislike the company's lies: for example, a one-hour flight will be advertising as leaving at 1 and arriving at 3, so it can run an hour late without a problem. You arrive at 2:45, and they proudly announce "another on-time Ryanir flight". That's why the company claims that it's the most punctual airline in Europe ... the other thing is that they claim to lose the least luggage, but really that's because nobody checks it in because it's so expensive! Well, apart from that, I can't really complain - for 30 euros you can go almost anywhere in Europe, and there are incredible 1c ticket offers sometimes. You have to be very flexible with dates, though. Valladolid Airport is about 10 km from the city centre, and here you can take Ryanair flights to Milan, London and Brussels. Actually the trip was quite comfortable. I had no problem with Valladolid airport, as it's so small it's impossible to get lost or confused. There is a small restaurant outside the waiting area, but once you pass through the security check, there's nothing but vending machines. There are also flights to Barcelona with Iberia, and Air France to Paris.
Alicante's airport opened a few years ago. This was a very positive development for the community since locals and guests can now enjoy all the comforts of a modern airport.
There are several transportation options: there are buses run by Alsa that go to Benidorm (9€) or Alicante city buses that cost €2.60.
This airport is ideal for flights to UK, Ireland, and continental Europe. For example, it's one of the few airports with year-round flights to Iceland.