All of these runs I have paddled and not if in a kayak then in a duckey or intra tube as a 12-16 year old.
As far as middle, north, and south cottonwood creek (also Morgans, Denny, and Ptarmigan Creeks) the runable sections are class 3 tree dodgin barb wire duckin runs with plenty o private property fun in a inter tube but not much more. Fishing is good but boating is bad. Just a hint but there is a plenty o first Ds in these drainages that would be sick with no trees and tons of water.
Chalk Creek has also been run everything but the cascades would someone get up there and run this same deal tons of landowners, fish hatchery, wood up the ars, and enough barbwire to start a farm with. The best thing about this run is that the very lower part makes Browns shorter.
Lower lake is the same kinda fun if huge barbwire to duck and a shotgun loving local who will confront you if you see him or disturb his ducks. If you want to run something up there just go about 6-7 miles upstream for the GOODS!
That stuff on the east west south fork of the north ark I have not run and I think that a crew went up there 3-4 years ago during high water and said that it was good to go.
If you want to creek in around the ark hit up Clear Creek super fun, Lake if you want to go big, or drive a hour and there are all the Butte Creeks.