Hike Mt. Tom, which is a beautiful area right next to the wedding venue. It was the inspiration for Mt. Krumpit it Dr. Suess' The Grinch, and looks out over the valley and the town of Easthampton (Whoville)... Then stop at Mt. Tom's Ice Cream in Whoville for top tier homemade ice cream and the full Who experience.
Downtown Northampton is fun to walk around! It features cute shops, great restaurants, and entertaining bars. Some great spots:
-Thornes Marketplace
-Progression Brewing Company
-Wurst Haus (it will be the Oktoberfest season!)
-Herrell's Ice Cream
-Tunnel Bar (Named one of Buzzfeed's bars in America you should drink at before you die)
-Jake's (Great breakfast)
-Packard's (a Northampton staple pub with a large billiards room)
-Northampton Brewery
-Joe's for great pizza
-Smith College Campus (amazing art museum and botanical gardens with free admission)
Just a few examples - there's plenty to do and explore!
Great food. Great Beer. 25 minutes from the venue.