the section you're talking about has long stretches of fairly calm water with a few significant rapids in between. From Pinnacle Rock to Parkdale is a Class III section that is fairly challenging for a new rafter. you may want to check out the section between Valle Bridge and Cotapaxi.
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