Anyone studied Spanish in Spain?

Hi there. I am interested in moving to Spain in September for at least 6 months to study Spanish (full immersion). Would appreciate some help in choosing a school, apartment, even a city. I have been to Spain a few times (Barcelona, Madrid, Valencia, Costa Blanca, Majorca) but not sure which city would be best for studying. So far Barcelona is at the top of my list. Your ideas and suggestions are greatly appreciated. Thanks again and happy travels.
Susan