San Sebastian is a superb beach location just west of the Pyrenees with excellent food (tapas). It should be on everyone's itinerary.
The Canary Islands are politically part of Spain, but closer to Morocco. The islands are mainly volcanic with a very pleasant spring-like climate year-round.
Málaga is an important tourist destination, known as "the capital of the Costa del Sol". An estimated 6 million tourists visit the city each year, who usually visit the birthplace of Pablo Picasso.
Santiago de Compostela is the capital of Galicia and the end point of the pilgrimage "Camini de Santiago" and the apostel James should be buried here. The journey here is different from other journeys since people like to either walk or bike.
Seville is the capital of the Andalusian region that also includes Malaga and Granada. It is very Spanish here with historical buildings, Flamenco Music & Dance, horses, Paella and Sangria. Note that it can be really hot (40°C and more) in Summer...
Cadiz is one of the oldest cities in Europe. It's location is quite unique, since it is surrounded almost completely by water (similar to Venice). James Bond used the city to resemble Cuba.
Jerez is known mainly for two things: 1) the bodegas for the finest Sherries and 2) the Equestrian School for ultimate horse back riding demonstrations. Add to this great weather, some flamenco and lots of orange trees and then you know something about Jerez de la Frontera.
Pamplona is best-known for its annual "running with the bulls"... Yes, these are real bulls and it is dangerous! Only the very sporty ones that have something to prove, should try this...