I have family members who made their way from West Virginia to Washington state. Guss Wayson, who was a brother to my great great grandfather, Ernest Wayson, went to Washington in the 1930's.
Not having any research experience in Washington, I cannot tell you how happy I was to have found a great resource for, not only vital records, but land, census, and military records too. There are also some court records, cemetery directories, and naturalizations that might help you in your hunt for Washington state family members.
Washington State Digital Archives has digitized many archival records of the state. Some contain actual images that are viewable as jpeg files, while others only provide transcribed data. For me, I was happy to be able to have access to either form.
The search engine is easy to use. In my case, I just entered the surname Wayson and found the marriages I was looking for and as an added bonus, found information that I wasn't even expecting! You can also enter first names to narrow down your search. There is also a keyword and detailed search which allows the selection of any record series and/or county.
If you have family in Washington, you owe it to yourself to give this website, Washington Digital Archives, a try.