Spanning from southern Connecticut up to the top of the mighty Katahdin, Best Hikes of the Appalachian Trail: New England, by local author Lafe Low, is a thorough reference to 45 day hikes on the Appalachian Trail in New England.
This is the only guide that specifically covers the best day hikes (suitable for expert hikers to families with kids) along the AT as it passes through Connecticut, Massachusetts, Vermont, New Hampshire, and Maine. The profiles include everything one would need to plan and proceed with a day hike on the AT: trailhead location, hiking time, hiking intensity, full description, directions, and maps.