i am assuming you mean greensboro, NC. in that case, check out the north carolina association of independent schools: http://www.ncais.org/
i absolutely agree that class size is the most important factor, as well as an emphasis on learning HOW to learn, and NOT an emphasis on standardized testing.
a word about montessori, though – i teach in a “classical” independent school, and we have had several students over the years come in maybe in 3rd or 4th grade from a montessori school who have had a tough transition to a more structured, traditional school. they often have difficulty focusing and persevering on tasks, and transitioning between tasks. IF you start your child in a montessori with the intention of later putting him or her into a traditional school, be aware of the possibility of this difficult transition.
the montessori approach DOES have its merits; please do not take this as an attack on montessori. i do not have any personal experience as either a student or teacher in a montessori school; this is simply what i have experienced w/ former montessori students in a classical school – just something for you to consider.