To see how well yurts hold up in PNW weather, contact the Oregon State Parks and ask about theirs.
This site
http://www.oregon.gov/OPRD/PARKS/rustic.shtml#RUSTIC_YURTS lists which of the parks have yurts. If they have some tricks or treatments that help them to hold up to the wet, salt-air problems there, they would probably be okay.
I stayed in one in September, and it was great! But Dave's arguments against them do tend to sound rational.
If you live in the Oly area or south, there is a Mennonite group in Rochester that builds wooden 'sheds' and can deliver and place them in sizes up to 12x16', which just happens to be eight square feet short of needing a permit to install. If it's a "shed".
Sue