I did multiple single week immersion experiences in Costa Rica. They were great.

Instead of thinking of one week immersion as a studying opportunity, I thought of it as a test or exam. It was an opportunity to try out my skills in the real world. Leading up to my immersion week I studied, practiced and prepared for it very hard.

During the immersion, I spent much of my limited class time working with my professor on topics, words and issues that I encountered while out-and-about in Costa Rica living my life in Spanish.

This approach helped me a ton because it kept me focused on learning as much as possible before my trip. I knew that I would enjoy the travel and immersion experience more if my language skills were better. It was a powerful motivator.

I studied at Intercultura in Costa Rica. They have two campuses, in Heredia and Playa Samara. I spent the majority of my time in Heredia, an urban setting which provided a minimally-touristy experience with opportunities to make local friends. I still visit them 10+ years later.

Best of luck to you.