Phil is right - Gulf Hagus is a must (it's my favorite run in Maine). I would add East Branch Piscataquis as a quality creek run. Smalls Falls is a great park 'n huck to check out.
While it's never very far from the road, the West Branch of the Penobscot could offer good overnight potential. It's still pretty remote, and it isn't uncommon to see moose and bald eagles with Mt. Katahdin in the background. There are various put-in, take-out, and camping spots to alter the difficulty and length of you're trip.