I assume your sons are not fluent in Spanish, am I right? If that's the case you will be limited to a couple, rather expensive, private schools where the classes are in English. There are a couple of them in the greater San Juan area that I know of, maybe in other towns like Ponce and Mayaguez as well. I can't really help you any further since my knowledge is dated - our youngest already finished college and lives in the States..
Outdoor sports like mountain biking are mainly in the countryside, in the central mountain range; English language schools are in the city. So you'll have to drive for either one. Now, if you have a job that's a third location to consider.
I would look for a place to live that's close to work and school. 