Since no one else has responded…
I think any website that provides reviews from people who have gone to the schools would be of interest to you. I’d start by Googling around using terms like ‘Spain spanish class review’ or ‘spanish courses madrid’ or something. Lonely Planet guidebook might also offer some info. I was able to get a lot of info doing this for spanish classes in Latin/South America. There’s got to be people discussing it somewhere online. You could also search for Spanish language courses offered through American universities and then talk to the folks that administer the programs.