Pat, a thing to consider when deciding what route to "The Coast" to take is where on the coast do you want to start (or does it matter)? Each route out to the coast ends in a different place. If you really want to do the whole Oregon coast (a worthy endeavor), then you should choose one of the two routes that go to Astoria, either US 30 or 202/47/Banks-Vernonia (which I heartily recommend.) Astoria is a cool little town worth a visit.
If you are more pressed for time and/or don't mind skipping sections of the northern Oregon coast, then you should use 6/8 or another southerly route like Nestucca River Road.
If you go via the Nestucca, give me a shout. You'll go right by as you head through wine country.