These are slightly off the field guide or science book list, more like "go here to see this."

Washington Wildlife Viewing Guide by Joe La Tourrette, Falcon Press
Visitors' Guide to Ancient Forests of Western Washington by The Ditttmar Family, The Wilderness Society/The Mountaineers Books
Old Growth Forest: A Casual Hikers' Guide by Charis Henry, BLM/USDA

I'm sure I didn't pick these up in your average Barnes & Noble. I agree with the suggestion of Flora & Fauna Books, and add the Seattle Audubon Society gift shop. I also picked up some of my titles (which have already been mentioned) at my travel destinations, like Visitor Information Centers, National Park gift shops, and shops in nearby lodges, towns, etc.

Marlene Penry
Ocean Shores, WA
mapste at coastaccess.com