Sounds like you're talking about the free flowing part of the river. It all floats really easy. I can't describe where the launches are but I've started upstream of Beaver and took out downstream of Beaver. I know that there are a number of ramps around there so get to a sporting goods store and ask some questions. Good luck, I really love that river.
Also, if you are talking about tidal. Follow the boats. There will be plenty right now. The ramp just east of the store in Pacific City is a pay ramp but never seems to be too busy.