I fish mostly the Oly Pen for them. Usually the southernmost off Chehalis system. We have alot of big chum, quite a few in the 20# range. I normally use straight leader from flyline, and usually 15-20# test. The way they fight (and the obstacles to boot) you need that tougher line. Normally, I'm only running maybe 3-4' off a sinktip line.
I use only a couple flies for chum. On rivers, I use my own chum bug alot (it's on a previous post I do believe) for most river situations, then on more stained water I use big flashy marabou type flies. Usually in chartreuse.