The school is great; modern, classy and located 5 minutes walking from the beach. What else could you ask for? The professors are nice and all genuinely concerned with your academic experience while there. Keep in mind, they know you're going to party and have crazy nights (very hard to avoid with the wild night life that permeates the Spanish/Catalan culture) but at the end of the day, they want you to to be able to reproduce what they taught you. If you are able to take integrated classes, do it, it will be a humbling experience for you. The Spanish students are very nice and welcoming, but you have to approach them first, as they will not go out of there way to do so. Just so you know, you will be that quiet, foreign kid (that sat in the back of class and never spoke up) your first few days as you take in all of the new scenery, teaching styles and language (even if you already speak Spanish) but it will absolutely change the course of your life and you will be better for it.
I am going to keep this short: You have the rest of your life to live in the States and do American things. However, you only have 1-12 months to live in Spain and might never make it back.
Go out, talk to the locals (even if you feel your level of Spanish is low, the only way to improve your oral skills is to practice), do what the locals do, imitate their pronunciation and body language, read the metro (free newspaper) while riding the metro, read Sombra del Viento on the beach, read Don Quijote wherever, speak only Spanish as much as possible (do not revert to English), try new foods (even if you have never tried a certain vegetable and "hate it" the Spanish cuisine have a way of making everything taste good), book flights to other countries ahead of time to save money, watch Spanish news and TV shows, drink café con leche, listen to passerby's conversations (be nosy and try to figure out what they're saying), drink Spanish wine, admire Gaudi's architecture, eat at Bo D Be and try not to realize how fast the time is flying by.