good answer....!there is a fair bit of flatwater. whether it's worth it or not, depends on what you want.
some fairly large GC style drops and then flat water in between. If you are looking for teh gnarz go hit up the SF Salmon to the Main. That would be fun.
When I raft it I am usually drunk so I don't remember much about the individual features. When I take my kids I will be sober and remember more. Huuuuuggggeeee sandy beaches that created a very hot zone between my shade and my beer cooler on the raft. Syringa will be popping all over the canyon and is an olfactory sensation for sure. One of the best smelling rivers ever.