I am thinking of the following ideas:
3. Is the Potomac north of Harpers Ferry a good bet? This would
allow sight seeing in Harpers Ferry.

There is much quiet water and good paddling above Harpers Ferry but be
aware that the last coupla miles (the Needles section) is lightweight class
2 but generally runnable. However, a definite rebar hazard from a broken
dam at its beginning is something to be avoided. You can take out before it
at Dargan Bend on the MD. There are also primitive campsites here and there
along the C&O canal which parallels the river.

I know that canoeing FROM
Harpers Ferry as far south as Monocacy is an excellent trip,
since I did it in the scouts once. Although I think that is
almost an overnight trip for a family outing... How rough is
the Potomac above Harpers? Perhaps we could put in around
the Shepherdstown area and head south to Harpers Ferry?

You would have to put in either at Dargan Bend as above, or else above
Harpers Ferry on the Shenandoah. In either case you will have whitewater --
and in the stretch below the Potomac you have a couple of not-for-beginners
rapids. You can, however, put in at the Potoma Wayside at the lower 360
bridge and get a nice run down to Brunswick for a shorter daytrip or further
on down to Point of Rocks.


4. What about the Susquehanna river valley in the vicinity of
Jamestown or Wilkes-Barre or (whatever the heck is up there)?

Very quiet (mostly) and scenic area up around Wilkes-Barre. There's a
PA Water Trail listing for that stretch. I don't have the url to hand but
check through the Pennsylvania DCNR websites for the water trail program.
There is much information up there. Look into the portions of the river
above Harrisburg.

Joe P.