Arcadia is the ONLY place to ride in RI. THe park has fire roads and singletrack all over the place. Some technical, some fast, all great. Still see it with my eyes closed. Get there soon. Don't confuse it with Acadia in Maine. It's ARCADIA!
Call Steadmans Bike shop in Kingston, RI for directions.
http://www.singletracks.com/item.php?c=1&i=419