I did this month long costa rica medical spanish immersion program in October.
http://www.adventurespanishschool.com/dominical_campus/index.html
I wanted to find a place that had medical spanish and was on the coast (i surf). This was one of the few that had both. The 'medical' component was totally dispensible from my perspective- the regular classes last for ~4 hours/day, and the medical classes were an additional 4-6 hours/ week- may not sound bad, but at the time, it was entirely too much, and didn't afford enough time to learn on our own and enjoy costa rica. Learning extra medical jargon and phrases is something I could've integrated into my own studies much more efficiently. After 2 weeks of living w/ a spanish speaking family and taking classes every day, i needed to spend less time learning grammer and more time practicing what i was learning.
Dominical is a small (~400 people) place, largely infiltrated by surfers/gringos b/c of the huge break there. After a few weeks, most people would be ready to leave and see the rest of CR.
If I were doing it again, I'd go to manuel antonio, costa rica (beautiful place, larger than dominical, perfect beach- better surf than dominical, more to do than go to dive bars every night, same proportion of gringos)- there are ~3 spanish programs there- i'd stay for ~2 weeks, do no more than 4 hours of classes/ day (preferably one on one), then rent a car and explore the coast or the mountains, practicing spanish along the way.
This was a wonderful thing to do as an MS4- I'd highly recommend it, it will be well worth the $2-3000 extra debt!