If you like cycling on busy, RV and tourist heavy coastal roads, by all means start in Astoria and take 101 south (make sure to avoid the scenic route from Fort Clatsop to Seaside). Wa SR105 and SR101 are boring roads that pass through miles of remote rural areas, typical ugly bays and obnoxious wetlands, noisy wildlife and a noticeable lack of typical convienant rest areas, campgrounds, car pullouts, all catering to the auto driving public.