Not through MCPS, but a few years ago I went to a language school in Costa Rica and have been thinking of taking the family along to do the same. There are a ton of them, and many offer homestay experiences along with formal teaching (I did a half-day of formal class when I went). Other half day is free to poke around the city, and on weekends they planned optional group excursions. I'm sure something similar is offered in other countries/languages. The homestay experience is a key ingredient-- much better than having US high schoolers hang out with other US high schoolers in exotic locales.