Seriously: stay in this apartment. It had the PERFECT location -- 5 minutes to the beach one direction and 5 minutes to Parte Viaje in the other. It was spotless, and the hostesses had thought of every comfort: slippers, extra toiletries, coffee capsules, laundry capsules, extra towels if needed...it was plug-and-stay all the way.
They were so communicative, available and kind. They let us check in early and keep our bags in the apartment a couple hours after check-out. They gave me advice about getting to and being in San Sebastian when I asked. On one of the rainy days I received an unprompted text from Cecilia giving me brilliant advice what to do in San Sebastian with inclement weather (aquarium, a spa that's located on the beach and you can run into the water to cool down!) -- just so thoughtful.
We were impressed, and if/when we come back, we know where we are staying!
P.S. Be aware that the apartment is kinda "cozy" so it's best for intimate friends or a couple rather than travel buddies.
Gracias para todo!