Hi Cozycamper,
Enso is one of many brands manufacturered by Zinus which is a Chinese manufacturer which tends to use lower quality memory foam (under 4 lb) in their mattresses and I would make sure that you know the density of every layer in their mattresses before you consider them. you can read a little more about them in post #2 here.
Unless you can confirm that there isn’t more than about an inch or so of memory foam that is less than 4 lbs in any of their mattresses you are considering I would tend to avoid them.
The closest list to you is the Seattle / Tacoma list in post #2 here. If I have the chance in the next day or two I’ll take a look around the Olympia, WA area to see if there are any reasonable options that show up on a more detailed search that are in the immediate area.
No matter how comfortable a mattress may be in a showroom, you can’t “feel” the quality of the materials so I would make sure you know the specifics of all the layers in the mattress to make sure there are no obvious weak links in the mattress and to be able to make meaningful quality and value comparisons.
The Costco mattress selection is always changing but my thoughts on them in general remain the same (see post #4 here). If there is a good quality mattress listed on their site (based on the specs they supply) then I would consider them if you are OK with rolling the dice (in terms of the suitability of the mattress) with the protection of a good refund policy and if the mattress you were considering was good value compared to the other similar options you have available locally or online.
Phoenix