How to plan Northern Spain 4 day trip?

I am really looking for a break away from it all - work, pressures... everything. I don't have the chance to get a lot of time off off work, but would like to go somewhere with my boyfriend for four or so days, most likely the North of Spain. How should I plan this trip? Tips are welcome... As are experiences.

You could go to San Sebastían. This is a relaxing and relaxed place to spend a short holiday. Nothing like the big resorts full of tourists, it has an authentic feel and you will really have the feeling you are on another planet for a while. They have ice foods, and a great beach. Clubbing is also fun over here, if you are into that kind of thing.