i'll probably wait until my kids are old enough to do allagash with me.The Allagash is out there for sure. I have done about 1/2 of it. Quite Beautiful up there. I do agree @StiHacka that the northern part of the state isn't as impressive as the Katahdin region.
The amount of exploring you can do on gravel roads on bikes is mind blowing. You just need to know how to read a map because they are are all old logging roads.
a buddy of mine did a hell of a trip up in the NMW in his FJ. from NH to deep NMW on all off roads / logging roads.