If you are traveling to or from Galicia this year, you may be using the new airport in Santiago de Compostela. AENA has a good website, explaining the services that the airport offers, but below you will find the basic information related to how to travel to/from this airport.
One easy way to travel to and from the airport is by bus. The airport bus leaves just outside the terminal and makes few stops (among others at the Santiago de Compostela bus station) before it stops in the Santiago city center. This buss trip should take about 20 minutes. This service is run my the Freire Bus company.
This airport is located 13km east of the city, direction Lugo from the city center. It should take about 15 minutes with normal traffic to drive out to the airport. The airport offers a large parking garage with 3400 parking spaces.
Traveling to/from the airport by taxi is the most comfortable way to do it. There is a fixed rate between the airport and the city (ask the taxi driver). One advantage with traveling by taxi is that he/she can drive you to the door of your hotel, if your hotel is locate din old town (where no car normally is allowed). This is comfortable if you have heavy luggage.
Enjoy your trip!