Hi PC88,
I changed this to a new thread so that others in the San Jose area will have an easier time finding it. Hope that’s OK 
The list also includes the better options I’m aware of as far south as the Salinas, Monterey area and as far north as Burlingame.
In addition to this list … there are also some good options available a little further north in the San Francisco list here.
Bay Bed & Mattress - FAQ A member here of this site. Factory direct manufacturer in Santa Cruz. Specialize in latex over innerspring “choose your own layer” mattresses. I have talked with them enough to know that they use the best quality components and offer great value, quality, and service and I believe compete well with the best in the industry. I think very highly of them and recommend that anyone within driving distance makes a point of paying them a visit.
Nest Beding Palo Alto, San Francisco, Albany, CA (and others outside the area). They are a member of this site and are knowledgeable, experienced, and transparent and carry a range of mattresses including latex, memory foam, and latex and memory foam/pocket coil hybrids. They have also put a great deal of time and effort into carrying mattresses that are good quality and value. I have also talked with Joe the owner on many occasions and he is passionate about what he is doing and left a larger manufacturer that had a somewhat exaggerated focus on “green” mattresses to form his own company because he wanted to “do it right”.
https://www.foamorder.com/ San Rafael, San Pablo, CA. Local factory direct manufacturer. I have talked with Alan here and he is committed to providing high quality materials and mattresses. Tends to focus more on the benefits of Dunlop latex over Talalay and some of the Talalay information here is I believe is somewhat inaccurate. They also make memory foam mattresses. Also well worth including in your research as they have some good options with good value. Their Natural Sense mattresses are also available at stores in Concord, Arcata, and Albany, CA.
http://www.mcroskey.com/index.shtml Factory direct “high end” manufacturer in Palo Alto and San Francisco. They hand build some very high quality mattresses using innersprings, natural and synthetic fibers but they also carry a premium price.
http://www.salinasmattress.com/ Factory direct manufacturer in Salinas. I have talked with the owner John and he uses some very high quality materials including latex, 5 lb memory foam, and higher density polyfoam. Good quality and value, mostly 2 sided (even with latex) and will also custom build. Good people
http://remsleepsolutions.com/ Factory direct manufacturer in Salinas. I have talked with Randy the owner here and they make some high quality memory foam mattress using high quality materials. They sell primarily through trade shows but have two company showrooms and a few retail outlets as well. He is very knowledgeable about mattress materials and committed to good quality mattresses and customer service but they also carry a more premium price compared to other smaller manufacturers that make similar mattresses so I would make some careful value comparisons.
http://www.thefutonshop.com/ San Jose, Los Altos, San Mateo, San Francisco, Concord, CA. Carries a huge range of futons of all kinds including innersprings, latex, memory foam, polyfoam, and organic wool and cotton.
https://www.gingerich-built.com/ Monterey Mattress. Independent factory direct manufacturer in Monterey. I would call first and check some pricing with a “rough description” of what you want as when I was talking to him about latex mattresses (core and comfort layer) the prices he quoted me seemed out of line.
https://www.thenaturalmattressstore.com/ Factory direct manufacturer in Los Gatos, Palo Alto, San Rafael, Walnut Creek, San Francisco. Makes a range of high quality latex/innerspring hybrids and all latex mattresses (including component latex mattresses) that can be customized both before and after a purchase. Worth a visit.
https://www.naturallyorganicsleep.com/ Burlingame. Local manufacturer that makes various “choose your own” layered latex mattresses with various different types of zip covers. Good quality and value. They also carry PalmPring, Pure Latex Bliss, REM Sleep Solutions, Restonic, Natura, Magniflex, Easy Rest, and Savvy Rest mattresses
http://selectsleepmattress.com/ Union City, Danville. Local factory direct manufacturer. This is a component mattress where you can “build your own” mattress by choosing a Bonnell coil, pocket coil, or HD polyfoam for a support layer and either memory foam, latex, or high density polyfoam for the comfort layers along with your choice of ticking/quilting for a cover. Good quality materials and good value. The owner used to be a licensee for a major manufacturer before starting on his own and building directly for consumers and is knowledgeable and clearly “mattress people”.
Shop Affordable Home Furnishings & Home Goods - IKEA Pal Alto. See post #3 here for more about their mattresses.
http://www.sc41.com/ Soquel, CA. Direct retailer for the Berkeley Ergonomics line of mattresses. These are a line of mattresses that includes all latex, latex over innersprings, and microcoil mattresses. They have good quality and value and the staff at the outlets that sell these mattresses are knowledgeable and helpful.
http://www.californiamattress.net/store-location/ Campbell, CA. Carries a range of high quality mattresses including Organicpedic, Pure Latex Bliss, Naturepedic, and Diamond but some of these are also in a more premium price range so make sure you make some careful value comparisons here.
http://www.sleephavenbedding.com/ Redwood City, San Mateo, CA. Carries Englander, Diamond, OMI as well as some mainstream brands I would ignore. I would also make some careful value comparisons here with their more premium latex mattresses.
http://www.diamondmattress.com/Diamond-Mattress/Default.aspx is a regional wholesale manufacturer based in Rancho Dominguez that makes a complete range of mattresses using all types of materials that have some good quality and value (depending to some degree on the prices of the outlet). They have a store finder on their site which will help you find the outlets that carry them that are closest to you.
The Ethos Refresh Medium by Diamond Mattress
This is the type of mattress construction I like and would be a good choice for someone who preferred the feel (or price) of latex over an innerspring as long as the model was good for both pressure relief and alignment. I like that the latex is on top without a lot of “junk” over it.
Simmons NXG 200
This has 1.5" of PurFoam (polyfoam) under 2" of lower density memory foam which is more low quality foam than I would suggest in any mattress. Like all the major manufactures … it is also overpriced and not very good value (compared to a mattress using similar materials made by a local manufacturer or available online). 2" of 3.5 lb memory foam and 1.5" of low density polyfoam is just not the kind of materials I would want in this price range. While it is not directly comparable to the Ethos in terms of feel because they use different comfort materials, there is no doubt that the Ethos is a higher quality mattress and would certainly be my choice between these two if they were equal in terms of pressure relief and alignment and anywhere close in price.
You have some good choices “in the area” but since many of them are not quite next door … I would certainly do some initial research on their sites and on the phone and then plan a trip to include the ones that interested you the most.
While I haven’t looked at every store in the area, there is little to nothing at places like mattress discounters or sleep train or famous mattress that I would even look at much less consider. At sleep world the only brand I would use for testing and reference would be the various Englander models (making sure that I saw the spec sheets to make sure they didn’t have more than an inch of polyfoam in the comfort layers).
Hope this helps.
Phoenix