If you run the Ark with a child who's never rafted before, you may want to either run from Johnson Village (launch at Wilderness Aware for $3) to Ruby Mt. (The Milk Run, all Class II) or from Stone Bridge to Salida or Big Bend (Class II w/ one easy Class III). These are a couple of the tamer reaches above Salida.
Have a good time!
Nothing in the world is more yielding and gentle than water. Yet it has no equal for conquering the resistant and tough. The flexible can overcome the unbending; the soft can overcome the hard. - Lao Tse