My advice to new expatriates coming to Chile has been, and remains, that people should spend six months in Santiago (or at a bare minimum three months) prior to moving along to their final destination. The reason for this is primarily two-fold: (1) you will not understand how Chile works or get a feel for life here, either in terms of economics, culture or political activism, unless you live a while in Santiago and (2) you will have an opportunity to go to language school by living in Santiago.
Spanish Classes in Santiago
My favorite language school is, and has been ever since I completed advanced language training in Santiago, the Goethe Institute downtown (which lasts three or four months). Visit the site and check it out. Today I saw another school that is near downtown also, the Escuela Bellavista which has a banner hoisted on their building that says “Spanish Courses” and evidently they have 21 years of experience. I have no idea how their school is compared to the Goethe Institute but it would be worth checking into. Look at their website.