Those sections above can be tricky especially the first time going through them. Any new river or section you plan on drifting it's a good idea to scout it on foot or go down it with someone who has done it before to show what to do. Or hire a qualified guide who knows what he is doing, it's money well spent and you'll live to tell about it.
On that note, there is a sectoin on the upper Skagit that can be a little tricky becuse it's towards the end of the drift and there are spots you have to be lined up just right along with some boulders you need to avoid. Fatigue becomes a factor here and probly a lot of you know what I mean, your up early, fish and row all day, then a tricky spot. Your tank might be on the empty side to pull out of it. Trade off with your buddy and let him/her row part of the day that keeps you both fresh and it lets others gain experiance on the river.