I am beginning to configure a ServiceDesk instance and need some advice on how to proceed with the sites/departments.  Essentially we will need to separate the sequesters for reporting and organization purposes.  

We are a department of about 10 technicians, and we service town users, and several schools.  I have read a bit about this, and have seen a few different ways to do this.  Should we configure each location as a site, or as I have seen recommended on here a couple times, as a region?

I have tried setting things up as sites, but am a little confused by the departments.  I don't seem to be able to associate departments with a particular site, so any advice would be appreciated.