Worcester: New England Backpacker, knowledgeable staff; this is where I buy when I need gear recommendations.
Boston: Hilton's tent city.
EMS: quite a few stores around New England, see EMS.com for locations. Their hq and warehouse is Peterborough, NH; they have lots of stuff online that's not in stores, but you can often pick it up in pboro if you call ahead.
REI: West Hartford, Boston, Reading (MA), Framingham (MA).