We started at Moabi Regional park by Needles. We started out under I-40, once under the last bridge is the entrance to the wildlife refuge. Along the route are some nice canyons, rock formations and some petroglyphs. Not to mention all the fish, bighorn sheep, burro, and even beavers.
There is no overnight camping along the refuge, except for fivemile landing, and that was not along our part of the trip. I remember reading somewhere, about 2 day trips starting farther north.
We Took out at Castle rock, a popular take out point. The GPS gave me a trip distance of 13 miles, as the crow flies.
Overall, a great trip for off season; but as boating season arrives it may become a different experience.
A couple links
http://www.fws.gov/southwest/refuges/Arizona/havasu/kayakingandcanoeing.html
http://www.moabi.com/gorge.htm