The one I carry with me most of the time is called 'New England Trees and Wildflowers' It's a very small "pamphlet" type guide, the large one I was referring to is an older 'encyclopedia' of trees I found in my parents bookcase but I don't remember the name of it. I have another field guide type book but it seems very general....
Sorry I don't know the names of them offhand, I'm away from home so I can't go check.
I just ordered:
Trees of New England-A Natural History, Fergus
Trees of North America, Brockman
Identifying Trees: An All-Season Guide To Eastern North America - Michael D. Williams
Master Tree Finder, Nature Study Guide
A Beginner's Guide-Trees and Shrubs of Northern New England, Steele
These should all keep me busy for quite a while....