For maps, as often as possible I use the Adventure Cycling Association route maps. I love these maps, and they have a lot of routes in the Pacific Northwest (probably because it’s such an amazing region to ride in). When those route maps aren’t available for the location I plan to ride, I scour the web and my library of touring books to see if someone else has put together a route for the region I want to visit.
A few of my trips have followed the west coast, and for those rides, Bicycling the Pacific Coast: A Complete Route Guide has been incredibly useful. I should note that I don’t like the section of the route that the book provides south of the Olympic Peninsula into Astoria, and I definitely advise against riding across the bridge into Astoria. There are better ways to complete that section, which I will cover when I post those routes.
For getting to the start of Adventure Cycling routes, I often use the rides found in Biking Puget Sound. Some of the routes they suggest are a little quirky, but they provide a good starting point for trip planning in the Puget Sound region.
I rarely use Google Maps or AAA maps to devise a route. Google Maps prioritizes direct routes, and bike touring is best enjoyed on scenic roads. AAA maps put you on the roads that suit drivers best, which are often not the roads that suit cyclists best. If I have to use one of those sources to find a route, Google Maps is preferable.
Each touring route I create will have a Maps & Routes section where I explain which maps I used and how you can get them. In some cases, mostly for the start and end of rides, I provide route directions taking you to the point where the map picks up or drops off. Unfortunately, not all bike maps start in Seattle.