When we moved a couple years ago we moved to West Greenwich for the school system. We actually looked at some comparable houses in Coventry, but at the time, the real estate + fire tax would have been like, 4-5K more a year than the house we ended up in WG. West Greenwich has a homestead tax discount, and I believe it's a 30% discount or something.
As far as Coventry goes, I have friends and family that went through the school system and haven't heard anything really negative.