Get San Sebastian For Mac
I would suggest driving. We drove from Santiago de Compostela to San Sebastian last year. The highway is great and the scenery is absolutely beautiful.
The 'best' way varies from person to person - fastest, cheapest, arrival time, etc. There are typically 2, direct trains per day from San Sebastian to Barcelona, taking about 6 hours (one in the morning the other in the afternoon). A full-fare ticket is €83 while advance-purchase tickets are as low as €33.
Things To Do In San Sebastian
Depending on how much time you have there are some great sights along the way. We stayed a few nights in Santillana Del Mar and did day trips to Altamira Caves, Comillas, Los Picos De Europa and Potes. I would also like to put in a plug for the Paradores in Spain. They are lovely. The one in Hondarribia outside of San Sebastian Is really something.Whichever you do enjoy the north of Spain. It is fantastic and not crowded.