IES Barcelona Liberal Arts and Business wasn't named the #1 study abroad program for nothing. So many course options (take classes at UAB - you are placed with kids studying abroad from all over the world), field trips, and student activities around the city are prepared for you.
Even if you don't speak any Spanish (I had taken French in high school), getting around Barcelona is not too difficult. The subway and bus system are amazing, so you can travel from one part of the city to another with ease. The food in Barcelona is also simply amazing. It is the most cosmopolitan city in Spain, so you won't be stuck with just traditional Spanish food. Catalan food is French oriented, but there are also Asian restaurants, Irish pubs, German food, African cuisine, you name it and you can find it.
I recommend taking out a student loan (or borrow money from family if possible) in order to have spending money for travel and eating out (eat out as much as possible, there is no city in America where food is as good as in Europe). I had a $6,500 student loan and spent about $3,000 on snowboarding trips to the Pyrenees and Alps (16 days riding in Europe total). The rest was spent in Barcelona mostly on food and going out with friends. Depending on your style, I would also suggest under packing clothes and buying some new threads in Spain. If you go for the Spring semester, the after Christmas sales begin in January and last all month and you can find great deals on just about everything.
One thing not to do is stay in Spain. Travel to as many countries as possible (Paris, London, Berlin, or any northern city in January/February will be cold -- check the weather before you travel) and eat as much new food as possible (especially Jamon de belota in Spain -- the expensive stuff, its worth it).