If you are heading that way there are lots of better little rivers to fish than the kettle. It is a fun float but we always did it in a tube with lots of beer. Watch the gorge though. A little rough on a boat of anything else.
Now far as rivers over there.....The Colville is full of large trout with good access all along the highway. Sheep creek is fun for small trout and all along the Pend is great.
For large trout you will get much better #'s on the Big C up by Wanita(sp.) border crossing. Once there it is about a mile walk down to the river but well worth it. Good Bows and even some dolly's. The best catching would be a boat on the Big C for walleye though. We have 50 to 100 fish days up there. Troll bottom walkers on ledges about 30 to 60 ft. Even throwing rapalas in the rocks, grass or about anywhere will get you some fish.