Seconding some of the highlights from this thread: Blackstone Valley bike path is very well maintained and is beautiful at any time of year, Stadium Theater is a historic site as is St. Ann's - both worth the trip (if they are open while you're there), the Museum of Work and Culture is excellent, as is Precious Blood Cemetery, which has monuments like the Angel of Grief, that rival those in nationally-renowned cemeteries like Sleepy Hollow, Swan Point, and Mt. Auburn.

As others have mentioned, although there are a lot of great restaurants, there's not a lot of vegetarian food on offer in Woonie. You might want to visit Wright's Dairy Farm, just over the line in North Smithfield and enjoy a pastry and some local coffee milk. Or try an ethnic restaurant like Swagat or the Boss.