El Colegio Puertorriqueno de Ninas is a good school. I seem to recall its tuition is about $7k per year but you should check for updated tuition costs. The school is in Spanish and as the name implies, only for girls, but they also teach English in the later grades.
I have been talking to many Puerto Rican and they all agree with you on how underrated Caguas is. One of my freinds who live in Dorado told me they are some very nice communities in Caguas.
