I declared FAS a few months back and though i'm only a freshmen, I can tell you what i think of it so far. First you chose which geographical area you want to study (Latin America, Europe, Slavic, Africa, Asia, and the Middle East). From there you'll choose one of the three FAS tracks (history, political science, and geospatial). I chose to go with a Middle East - PolySci track. Personally I liked the offering of polysci classes while the other two tracks just didn't appeal to me that much.
When you graduate, you come out with a Major in FAS and a minor in whatever language you took. As a whole, the major covers a large variety of topics from culture, history, society, politics, geography, etc. No matter what track you choose though, you get a little taste of each.
Another perk of FAS is that you have a better chance to be chosen for immersion trips to other nations (either for a semester or just a summer period). Though doing FAS is not a requirement for applying, it does look good on the application. Even as a freshmen, I've already been chosen to go to Tunisia this summer for an immersion, which was in large part to having chose FAS.
Hope that helps. Feel free to ask anything else and if I know the answer I'll be glad to answer it.