If you are interested in studying Spanish while you are in Buenos Aires you should consider getting a textbook from the University of Buenos Aires.  The textbooks are used by the Spanish program at the university and are great. They focus on Argentine society and culture and will really help you identify with and speak like the Argentines. I took a Spanish class here and found it really beneficial (more information can be found here). If you don’t want to take a class you can still buy the book and study it by yourself or with a private teacher.