One of the best kayak tours you can do is from Hoover Dam to Willow Beach AZ down thru Black Canyon.You can book a tour to take you downriver(you need a guide service to drop you off because the dam is private Gov't property.) Or you can paddle up yourself from Willow Beach.
The scenery is great,lots of historical stuff left over from Dam construction like the catwalks bolted to the canyon walls,the trolley over the river to the gauging station...
Also there are several hot springs.Arizona hot springs has a primitive campsite and a ladder that leads up to the spring.Goldstrike Canyon on the NV side has a nice spring too.