We stay at Caribbean Jewels - Ajax Peak a few years ago. We've traveled many times to STJ, and thought this had an ideal location. The house is beautiful and pretty much right in the middle of the island. Both bedrooms are gorgeous and there is a third powder room. It is very private, a dirt road off of centerline takes you to the house. Don't let the dirt road scare you, there are some beautiful views and the driveway is paved. There is another house below, but that was not an issue.
http://www.destinationstjohn.com/home.php/8/Caribbean+Jewels