-- Last Updated: Jun-07-11 10:23 PM EST --
The West Branch Penobscot above Chesuncook Lake is a fine trip. I think it can be "crowded" during the spring and fall fishing runs especially, but otherwise "crowds" are relative. You may see a few folks. I spent a week on Lobster Lake once the first week in August once and saw one other person - a Ranger.
The rapids below Ripogenus Dam can be very serious depending on the water level.
The fees for the State of Maine Penobscot Corridor are collected by North Maine Woods, but are different than North Maine Woods fees if that makes any sense.
Bugs are Bugs. Make peace with them, feed them, enjoy the woods, sprinkle them on your oatmeal, bring some dope if you need it. ;-)
If you plan to spend much time driving on the roads, bring a good spare tire. I lose a tire every trip or so.