I have now been to five of the stores listed in post #2 of this thread and thought I would provide a few impressions.
Ikea
See post #9 here.
Healthy Back
See post #18 here.
A Bedder Bed
Lots of innerspring options, many with memory foam on top, from Boyd and Spinal Comfort, many in the lower-budget range. The only bed currently on display containing any latex is the Lavendar Latex Hybrid
ADMIN NOTE:Removed 404 page link | Archived Footprint: abedderbuy.com/2013/lavender-latex-hybrid-mattress/
The pillowtop on this looks even thicker in person, maybe 4", and felt soft to me.
I was privileged to speak with Escondido About page who has been making mattresses for 60 years. You can see the giant sewing equipment in the back room. Randy can make you a two-sided innerspring mattress and box spring “like they used to.” His says his latex is all-natural talalay from Sri Lanka. He will sell you a latex topper but he does not layer latex in mattresses: you get a solid 6" slab. I asked him about ILD and he quoted something like 85-90, so obviously a different scale. I asked what he thought of memory foam; he said that it was made for the space program and they should have just left it in space. 
Euro-Flex
This unassuming storefront down the street from Costco opens onto a good-sized showroom with LOTS of latex options. They have all-latex beds (solid and layered), latex over innerspring, latex over an air bed, and latex over a Röwa adjustable bed with a stretched canvas (?) “trampoline” platform. It’s all either blended or natural talalay by Latex International. This is the first store I’ve found where the staff was conversant in ILD numbers and could unzip the side of the mattress and tell you the densities of each layer. Probably because they assemble and customize their own mattresses. Higher-end stuff but not opposed to discussing economic options.