I think you'll really enjoy a trip to Burlington. It's right on Lake Champlain. In town, there's lots of shopping both in an underground mall and outdoors along streets that have been permanently closed off. Just a short drive away there is another mall as well.
Do you know where you'll be staying? I could try to give you more specifics of what would be nearby.
You can either take a ferry across Lake Champlain
www.ferries.com or go on the Spirit of Ethan Allen for a scenic boat trip.
Spirit of Ethan Allen The Boathouse is a public park area in Burlington that is also quite nice to wander around.
The Shelburne Museum
www.shelburnemuseum.org and Shelburne Farms
www.shelburnefarms.org are great. The restaurant at Shelburne Farms is good. Downtown in Burlington the New England Culinary Institute runs a restaurant that is also terrific. Or, you could head out to the NECI's nearby hotel, the Inn at Essex and try the restaurants there. The Sunday brunch is to die for. There is also some outlet shopping in Essex Junction but it is not spectacular.
Burlington also tends to have lots of concerts and festivals going on in the summer.
I may be taking your knowledge for granted but Burlington is also the home of the University of Vermont. You might want to explore the campus a bit, too. There are several other colleges also located in and around Burlington