For those desiring wild rivers in the Northeast, consider the Adirondacks, a gentle, grizzly-free wilderness with some darn good bubble-boating. Highlights include:
The West Branch Sacandaga River
Great whitewater trip through the Silver Lake Wilderness Area with many possible approaches and a remote gorge that is really only doable by class V boaters or packrafters who can bushwack/scramble around it. For a daytrip you can do the whole gorge plus the Whitehouse to Wells section or just put in at Whitehouse. The gorge section is described here: http://americanwhitewater.org/content/River_detail_id_540_ The Whitehouse to Main Branch section is seven miles of near continuos II-III. To portage around the gorge you can bushwack on the south bank away from the river (the fastest) or scramble along the faint trail and cliffs on the north bank as a more scenic option. For an overnight trip hike the Northville-Placid Trail from Upper Benson and camp at a lean-to at Silver or Mud Lake, or hike the NPT south from Piseco where you can stay at the Hamilton Lake Stream lean-to which is another possible put-in leading to the West Branch. The river seems to be at a good level when the gauge at Hope http://newweb.erh.noaa.gov/ahps2/hydrograph.php?wfo=aly&gage=hopn6 is around 2.7-4 ft, which happens in the spring, fall and after storms.
West Canada Wilderness Area & Moose River Plains Wild Forest
Lots of rivers, lakes and trails make some more ambitious trips possible in this area. Good packrafting rivers include the Cedar, South Branch Moose, Indian (from Brooktrout Lake), Jessup, and West Canada Creek. There are many possible approaches and connections via trails (Northville Placid Trail, Brook Trout Lake Trail, Sucker Brook/Colvin Brook Trail), lakes, and bushwacks. This area is best packrafted in late April or May before the black flies when the water is high and the dirt roads of the Moose River Plains are closed.
Other Adirondack possibilities include a High Peaks traverse to the Hudson River Gorge, the big whitewater of the Moose River and numerous canoe routes on the Raquette, Oswegatchie, etc.