I have seen plunkers off powell road as well - there is small little sand bar on the bank with a trail leading to it. just as you come down a little hill to your left. but, I used to plunk alot and we always plunked lower in the river (usually in tidewater), especially when the water is lower as you are looking for moving fish when you are plunking. the spots mentioned would be good when the fish are coming in, but even then I would go try down lower maybe by carnation as that gives you a shot at the fish for all three rivers passing by. Just at the end of town (the end towards duvall) there is a bridge and I use to see alot of guys plunk down there, have not fished down that way in a few years but I bet they still plunk there. Pretty easy access also, not far from the truck.
They also plunk on the corner right behind the ball fields in Fall City. when the fish are in there are alot of guys there right on the corner.