I rode the coast from Seattle to Santa Cruz many years ago. I followed the route in Bicycling the Pacific Coast. I turned south at Montesano on 107, then joined 101 south and followed it all the way to Leggett Hill. The book is a bit out of date but still very useful. The last time I rode the coast I photocopied the pages I needed and threw them away when I was finished.

Oregon also has a bicycling map which is very useful.