Maine is a great place.  I lived there for a long time.  There are a number of great canoeing places.  Lobster lake is one of my favorites off the West Branch of the Penobscot river and then up Lobster Stream, a little combination of river and lake paddling with lake camping, great beaches and clear water. The roads in the area are dirt but excellent since they are maintained by the logging companies. Sebago Lake is closer to civilization and the Songo river between Sebago and Long Lake offers a fun day trip including a set of locks that the old mail steamers used to use.  The Songo locks are operational and you can take a canoe through them.  Then there is the Saco River from North Conway, NH all the way to Saco, Maine. It gets scratchy in the upper reaches in the late Summer and Fall but has some excellent canoeing most of the year.  Maine has so much water that you can't go very far without bumping inot a river or a lake.  I you have some regions in mind let me know and I can give you some ideas.  

Regards,
Chuck