Before you get to Salkum you'll see a tackle shop on the right called "Fish Country" The folks there are helpful and friendly. They also have hand drawn maps of the river. There's not much going on on the Cowlitz at the moment but, if you have any experience with a drift boat at all, this is a good place to learn. Otherwise, go with the previous placid water suggestions because:

You must learn to spin the boat without having to think of which oar goes forward and which goes backward.

You must know to point the bow of the boat at the thing you want to miss so you can PULL away from this thing that might eat your boat and drown you.

You must learn to read the current so you don't row your guts out in the slow water.

Finally, when you are on a new river and the water in front of you looks tricky, land the boat and walk down the bank so you can take a good long look without having to make a snap judgement and maybe making a bad mistake. This goes for any river that you have never floated before. It's okay to be a little chicken on a big river like the Cowlitz. Don't let anyone push you into doing something you feel is dangerious.

Feel free to email me if you want to continue this discussion in private. I fish the Cowlitz quite a bit.