Here are two classrooms at CISA language school http://www.cisacostarica.com/. In this photo one class is directly above the other and they are open air. Very cute and efficient. Classes are small with no more than 3 students to a teacher. Often just one student to a teacher. This gives you the most intensive course possible.
I have recommended CISA and I totally believe that this is the best place to learn Spanish in the most beautiful setting, with wonderful instructors in Costa Rica. If you want a real cultural experience, that is not in gringo Costa Rica, this is it, the real deal, in rural Costa Rica. You will learn sooooo much more than just Spanish. Like April, you will not want to go home.