Hi Eiderdown,
I changed the title of this thread to reflect the area you are in to make it easier to find for others from Washington State. I hope that’s OK 
Here are some of the places I know about in Washington state including factory direct manufacturers with some comments included …
Seattle/Tacoma area
https://www.soaringheart.com/ Local factory direct manufacturer that is a member of this site. Builds organic customized sleep systems (mattresses, futons, and shikibutons) using organic Dunlop latex, innersprings, and various wool or latex comfort layers or toppers. While they are in a higher budget range they are also very high quality and well worth including in your research for those who are looking for high quality natural or organic choices or for some of the unique qualities and performance of their designs. Jason and the staff there are very knowledgeable, helpful, and open about the materials they use and they make sure that all the “fine details” are done right.
https://slumberease.com/ Local factory direct manufacturer in Marysville, WA (they have a factory location and a retail location there). I’ve had several great conversations with the owner Nick and he is very knowledgeable, informative, and helpful. Best of all they take the time to fit a mattress to a customer and they will even custom build including side to side splits. He is clearly “mattress people”. They have great value as well and would be well worth a visit. They are also in partnership with http://www.eastsidemattress.com/default.asp which is owned by Tim and works together with Slumber Ease and makes the same or very similar mattresses and uses the Slumber Ease showroom for local customers. He specializes in helping people with more difficult challenges such as fibromyalgia or chemical sensitivities and is also very knowledgeable about mattresses, materials, and helping customers choose a mattress that is the best “match” for them.
http://www.foamrubbercity.com/ Local foam shop and factory direct manufacturer in Kent, WA. They are a small business owned by “Earl” who is what I would call an “expert” on all types of foam. They sell latex, memory foam, and polyfoam in all types and qualities and what they don’t have they will source. They have some mattresses in their showroom to test different materials and will custom build to your specs and application. Good value and well worth a visit for either a mattress or foam materials.
http://www.mattress-makers.com/ Parkland Sleep Center. Factory direct outlet owned by Custom Comfort in Tacoma, WA. Have been building mattresses for 30 years. They don’t use anything less than 1.8 lb poly and will custom build (but then it’s yours). They are not as transparent about layers and materials because they believe it can harm them so we had a longer conversation about this. They carry pocket coils with Dunlop latex on top and also a dunlop/memory foam hybrid over an innerspring. Will add a lower gauge firmer spring when needed. Good people but could use more transparency IMO.
http://seattlenaturalmattress.com/ Factory direct manufacturer in Seattle. They make a very nice natural Dunlop (and organic latex) layered latex mattress. They are an offshoot of Mulligan Mattress in Oregon. They also make a very nice simple slatted wooden bed that can be used for a base.
seattlemattress.net/contactseattlemattress.html They are a local factory direct manufacturer in Seattle who also carries other brands. They are also very helpful and knowledgeable and I did quite a bit of mattress testing here however they are more expensive than most local manufacturers (probably so they can sell other brands) and I would make some careful value comparisons because they may not have the same value as many of the independent manufacturers that I have dealt with.
ADMIN NOTE:Removed 404 page link | Archived Footprint:seattlemattress.net/contactseattlemattress.html
everestmattress.com/ Factory direct manufacturer in Seattle and Marysville. Was originally run by the father but now is run by the daughter and her mother when he passed away. When I talked with the daughter the conversation was quite different from most of the conversations I have with family owned manufacturers who normally are very happy to share with me what they do and how they make their mattresses. She seemed to be more of a business person than a mattress person. Perhaps she was having a bad day . There does seem to be some good value here in low to mid range mattresses from what I can see.
ADMIN NOTE:Removed 404 page link | Archived Footprint: everestmattress.com/
https://bedroomsandmore.com/ They are a retail outlet or “sleep shop” in Seattle where I also spent a lot of time testing mattresses. They are very helpful and knowledgeable and are close to and compete well with Seattle Mattress who is nearby and carry their own custom latex mattress. They carry their own line of Dunlop latex mattresses called 45th street bedding along with Oregon Mattress CO, Englander, and Therapedic and OMI. They have a wide variety and are a good place to test mattresses to get a sense of what works for you, are knowledgeable, and good people.
https://www.holylamborganics.com/ Oakville, WA. They carry a range of high quality organic latex, innerspring, and cotton / wool mattresses including WJ Southard and toppers that they manufacture themselves. Some very good quality here and knowledgeable people.
http://www.sixdaymattressstore.com/ Another retail outlet or “sleep shop” in Redmond and Issaquah, WA with exceptionally helpful and knowledgeable people and ownership and sell posh + lavish latex. They are also good people.
http://thesleepstoreusa.com/ Retailer in Bellevue, WA. They carry a range of alternative brands including, Renelle, Electropedic, Savvy Rest component latex mattresses, Naturepedic, Sleepcraft, Palmpring, Suite Sleep and others. A good place to get a sense of the difference between Talalay and Dunlop mattresses and the people there are also knowledgeable and helpful.
Contact - Friendly Foam Shop Foam shop with locations in Seattle, Bellevue, and Everett. They carry a range of polyfoam, memory foam (up to 8 lb density) and 100% natural Dunlop latex and can put different layers together to try. They also sell some covers. They also carry a specialty mattress from Squire Sleep with a slanted surface and a shoulder cutout which is in a more premium price range.
404 Not Found! Silverdale, WA. they carry Pure Latex Bliss hybrid and Talalay latex mattresses, 45th Street Dunlop latex mattresses, and Easy Rest memory foam mattresses. Good people with some good selection and focused on knowledge based selling.
Shop Affordable Home Furnishings & Home Goods - IKEA Renton, WA. See post #3 here for comments about their mattresses.
South West Washington
https://parklanemattresses.com/ Local Factory direct manufacturer based in Tualatin, OR with an outlet in Vancouver, WA. They have great choices and value (which is why I invited them to be members here). They make high quality products. I took a drive from near Tacoma (which is where I live) just to visit their factory outlet in Tualatin and test their mattresses and I’m glad I did because there is some great quality and value there.
Eastern Washington
nwbedding.com/store_locations.php Local factory direct manufacturer in Spokane that makes good quality products based in Spokane. They used to be a licensee but have “gone back to their roots” as a factory direct outlet. They make “all talalay latex” mattresses with no polyfoam as well as a full range of all types of mattresses and are happy to provide the layering and information about every layer in their mattress.
ADMIN NOTE:Removed 404 page link | Archived Footprint: nwbedding.com/store_locations.php
https://www.twilightbeddingfactory.com/ Local factory direct manufacturer in Spokane. Makes a full range of mattresses including memory foam, latex, and custom builds that have good value. Paul is the owner and is well worth talking to.
Furniture Row® Store Locations - Store Hours & Addresses Regional factory direct manufacturer. Carries a range of mattress that they make including latex options which use good quality materials and have good value. I would ignore the major brands they also carry.
higginsonsflooringandsleepshop.com/ Retail outlet in Pullman. I have talked with them on the phone several times and they too were very helpful. They carry Pure Latex Bliss which is a high quality line of talalay latex mattresses which are among the better quality and value national brand mattresses and they also carry Easy Rest which are a Chinese manufactured but CertiPur certified line of memory foam mattresses that uses some higher density/quality foam and has good value.
ADMIN NOTE:Removed 404 page link | Archived Footprint: higginsonsflooringandsleepshop.com/
https://www.manta.com/c/mrl7ngv/comfort-city-super-sleep-ctr Coeur d’Alene. Smaller retailer that carries Easy rest, Restonic (incl their gel memory foam), Pure Latex bliss, and Lady Americana.
Redirecting... Retailer in Spokane. They appear to carry Savvy Rest which are a high quality “choose your own layer” latex mattress which allows you to customize your own mattress but also carries a premium price so make some careful value comparisons here.
South Central Washington
mattressfactorynw.com - mattressfactorynw Resources and Information. An Oregon based factory direct manufacturer with a factory and outlet in Moxee. They make a range of mattresses including a 6" Dunlop latex core finished on both sides and also carry Natura mattresses (which are primarily high quality latex and latex hybrid mattresses that are great for testing but not so great value).
Furniture Row® Store Locations - Store Hours & Addresses See description in Eastern Washington.
Kitsap Peninsula
See post #2 here.
Northwest Washington
See post #14 here
Olympia
See post #5 here
Bellingham
See post #14 here
Hopefully this should give you some choices as to the value that is available in and around Seattle and/or Washington State. A few phone calls to some of these once you have a rough idea of what you are looking for should help you decide where the best value may be for your circumstances. The mass market stores and the chain stores in the Seattle area do not carry the same quality or value as most of these and I would “pass them by” in most cases…
Phoenix