Spain is really relaxed and fun, especially in the summer. I studied at a language school in Alicante last summer and it was great fun but, of course, through school you met more foreign students than spaniards. It's all about your own attitude, americans who go around telling people how they, unlike europeans, are free(some of whom I've unfortunately met) probably won't make too many local friends. So don't worry, you'll have the time of your life!
This summer I'm going to Cádiz for a month, has anyone got any experience from studying there?