San Sebastien is all about pintxos (or high-end, Michelin-starred restaurants). I believe they actually have the most Michelin stars per capita than any other place in the world. The old city is absolutely stunning and easy to walk around in.
Eateries
Here's a look inside the world of pintxos.
Gandarias Jatetxea - this was a great segue into pintxos. They had a wide range of options, which were all delicious, and you can sit down and linger (a lot of the pintxos bars are standing, and you throw your garbage on the floor when you're done…this was not an easy concept for me.)
http://www.restaurantegandarias.com/en/
Ganbara - The fresh mushrooms here are amazing! Get them with an egg yolk (assuming you like mushrooms and soft eggs).
http://www.ganbarajatetxea.com/presentation
Borda Berri - OMG the beef cheeks! There was also some risotto/orzo dish that was a must.
La Mejillonera - The mussels with red sauce and patatas bravas were the way to go!
La Cuchara de San Telmo - This was definitely one of my favorite pintxos bars. The food was top-notch.
Somewhere in the middle:
Extebarri - I cannot say enough about this restaurant. It was probably my favorite meal in SS and still in my top five. It's about an hour outside of San Sebastien but SO worth it. The chef smokes some element of every course and is incredibly talented. The drive is a windy one, so we went for lunch, which worked perfectly because we didn't have to worry about doing it in the dark and could easily get a reservation.
http://asadoretxebarri.com/en/
Restaurante Rekondo - I believe this restaurant has one of the (if not the) most extensive wine lists in the world. The food was delicious, but it's really about the wine here.
Fine Dining:
Arzak - This is one of many tasting menu experiences in San Sebastian, so it was tough to pick just one. It was an incredible meal, and I would definitely recommend it. We were 100% happy with our choice.
I did a "gastronomy trip" through San Sebastian Food, which was great. Their experiences are really creatively curated (picture attached) and well thought out. It was a great way to emerge ourselves in the pintxos scene because you can use the "tokens" at some of the best places.
http://www.sansebastianfood.com/en/food-tours-and-events
If you're looking for a day trip, check out Rioja, which is not far if you want a taste of wine country.