Adventure Cycling's Trans America section one map covers the route between Florence and Eugene and has all the info you would need for that section. The rest of your route is covered in both AC's Pacific coast route and the book already mentioned by Valygrl (Bicycling The Pacific Coast). The book may be starting to get a little out of date for some of the services since it was last published in 2005.

Alternately you could map the route on mapmyride or biketoaster and could even use AC's gps files (they are a free download). Someone even has google earth files on the web for all of the AC routes. A Google search should turn them up.