If you take the decision to send your 3 (gulp!) children to one of the better local "colegios" that limits your choices:
1) The elite--Da Vinci, Juan XXIII (on PUCMM campus), La Salle, Sagrado Corazon and Colegio Dominicano
2) The no-so-elite: Colegio Evangelico, Padre Fortin
3) The "forgetaboutit" group = all the rest. Which is not to say that some of these won't work. You just need to be more careful.
4) I noticed that "extra" was also on the table--there are places called "Sala de Tareas" and an some very good English schools around (EFI- Dominico-Americano-JFK etc)...
One interesting thing is that the "Elite" group and the "Not-so-elite" are all located along the same roadway: Juan Pablo Duarte (with the obvious exception of the Juan XXIII on the PUCMM campus). Colegio Dominicano is on the old highway to Moca, about 15 minutes (little or no traffic) from center city. Da Vinci is located on the road to Don Pedro (going to the left at the traffic circle at the eastern edge of Santiago-across from the Bulevard Plaza--which is parallel to the old Duarte Highway.
Then you have Padre Fortin--close to the Materno-Infantil Clinic; Colegio Evangelico--across the street from the Ayuntamiento; La Salle, and the Sagrado Corazon.
Pick one. I like the results I see from Da Vinci and La Salle, which are 12 year schools + pre-school, so you get kids that have been fairly well trained all through one school's system. None of them are particularly "religious", with Da Vinci being the most non-sectarian and the Evangelico, obviously, a bit more centered on religion. Colegio Dominicano is also fairly non-sectarian, although the founder is a former priest. (And one of my favorite students, all time, is from there, so they can produce good product).
HB