Blue Devils: Mansfield HS 20 mins from Gillette
Cadets: Dartmouth HS 75 mins from Gillette
EC Jazz: Bishop Feehan HS in Attleboro 20 mins from Gillette
Crown: Mashpee HS, Cape Cod 60 mins from Gillette
Bluecoats: North Attleboro HS, 15 mins from Gillette
BAC: somewhere in Lexington
Spirit: Norton HS 25 mins from Gillette
Cavies: Case HS, Swansea, 30 minutes from Gillette
Madison: Austin Prep, Danvers (I think) 60 mins from Gillette
Phantom: Manchester, NH--but closed to the public
A nice small circular practice tour would be
Blue Devils, Spirit, Cavies, Bluecoats. They're all within 30 mins of each other, just south of Gillette and easy to get to off the highway.
Hope this helps.
Tim