If you ever visit Donastia San Sebastian, and it should be on everyone's bucket list, you should definitely try and stay at Monique's Apartment.
Monique is the ultimate host and the Apartment is stunning and right in the middle of the Old Town where the pinxtos bars are. It is also only a short walk to the beach and the New Town.
Would also definitely recommend going on a walking tour to learn about the history of the city.