I've been Clarno to Cottonwood at 20k+. Clarno Rapid is a fun ride of big roller waves that goes on for 1/2 mile or more, and Basalt rapid is more interesting than normal flows just because it is all moving and some of those big boulders create hydraulics. It doesn't take very long to make big miles, so you can do that lower 69 miles in three days really easily.
In addition to the muddy water and whole trees that Shap mentioned, expect to see a few dead cows floating along as well. On our trip a few years back the water was high enough at Cottonwood that we could float right up the ramp corridor and into the parking lot, making for plenty of room to de-rig!
The camps down there are all up on benches anyway, so camps getting washed out wouldn't become an issue unless it went significantly higher.
Show me your OOOOOO face