My wife and I have stayed in Sitges, Spain many times, almost always in December and January. Our favorite restaurants in Sitges are La Torreta, El Velero, and La Nansa. In nearby Barcelona Set Porte is always amazing for serving locals and tourists in a correct and professional manner with wonderful food and an atmospheric setting. We also get great takeout food from a small shop just off San Sebastian beach in Sitges-real Catalon cooking at a price you can't beat.
We have also made a daytrip to Vic which had cured meats and cheeses to match anywhere else and a town which seems to me to be northern Italian at its best.
Also, Avila had great fresh seafood every morning from the three seas around Spain and their local beef is very special.
Our two days in each of Bilbao and San Sebastian showed us why Basque cooking is so praised and the market in Barcelona (La Bouqeiria) can be matched only by the main market in Valencia.
The white wines of Rueda (no oak and videjo grape) are the best and inexpensive and cava from Catalonia is the same.
Fried artichokes with lemon and salt and cava at La Nansa is the top of the hill.
Anything to add?