One of my secondary passions is education. I suggest that you sit down to analyze which Dade Schools are currently filling to max capacities, which is the way the school board calculates where new schools will be needed in the coming years... and in your case (as I'm assuming that the Montessori School will be private), which of these neighborhoods would also support your target parent income.
But then again, you're the expert in building the schools, so I'm also assuming that you already know a little something about all that... ;)
Nonetheless, Miami is a very big place, and it is my opinion that once you know where you need to be, finding the right property and negotiating the price will be a whole lot easier.
Hope that helps!