I went to the old Uruguayan-American School on Calle Dublin, and had many friends at the British School of Montevideo. The important thing to remember is that these schools are not just about the language, but the cultures. From dress codes, to holidays, the music, arts, etc., you must consider what the kids will adapt to the best. As an American, UAS was a great fit for me, but with the size of the expat communities, you end up socializing with most of the other expat groups. I ended up dating girls from the UK, Italy and Germany. I found myself in a kilt dancing reels, jigs and waltzes. Uruguay is a WONDERFUL country full of amazing people, and anyone who is open to it will have a life-changing experience. I'm trying to retire to Uruguay in the future.
Cheers!