Adding to the plethora of comments about visiting Mass MoCA and the Clark Institute, I'd recommend another stop: head over to Route 2 in Troy, New York, and look for the restaurant Ali Baba. It's a nice little Turkish place in the middle of "student slums", and it's a must-stop for lunch whenever we are in the area.
I recommend the Route 2 path into Troy because it passes through the Tacoma Ridge State Forest and offers plenty of nice twisties. If you travel from Troy back to Williamstown in mid to late spring, you see a vivid demonstration of how seasons vary with altitude. At the bottom of the mini mountains, you'll see the leaves with the rich green color of spring, and as the altitude climbs, you'll notice that the trees become the pale yellow of early spring, and sometimes the trees at the top are just buds.
If you're coming from Boston, I highly recommend stopping in Shelburne Falls to visit the Bridge of Flowers. Downtown Greenville has some nice antique stops. Tucker Falls. Theoretically, it has fossil beds in the area, but I've never actually gotten around to visiting them. Zoar has a nice zipline setup, but it's sufficiently popular that you'll need to make reservations.
The trip from Boston via Route 2 to Williamstown is a great way to spend a weekend. The North Adams/Williamstown area is a great place to spend a weekend. I've always enjoyed doing that.
Although, come to think of it, we are approaching maple sugaring season, and there are some good places out there to blow out your pancreas with fresh, rich Grade A dark New England maple syrup.
