Hi tahoebigah,
I’m glad you made it to the forum … and welcome. I hope you’ve had a chance to spend some time reading the tutorial post and the many links it contains because it deals specifically with many of the comments you’ve made … but I’ll add a few more comments and links here that are specific to your comments.
One of the most important part of making a good mattress choice is knowing how to test a mattress so that your testing has higher odds of being a good match for your actual sleeping experience. The tutorial includes several links about how to do this. Buying a mattress based on “showroom feel” alone has lower odds of buying the most suitable mattress than random chance alone (see this study) and unfortunatel you can’t “feel” the quality of the materials in a mattress because lower quality and higher quality materials can feel the same … at least for a little while.
Again … the tutorial post goes into much more information about why the major brands aren’t the best quality or value choices and it has nothing to do with the size of the company. Outside of the suitability of a mattress in terms of PPP … the most important part of a mattress purchase is the quality of the materials. There is little value in buying a mattress that feels great in a showroom when the feel and performance of the mattress only lasts a few years (or less) before it needs to be replaced and the foam softening that leads to the loss of comfort and support isn’t covered by the warranty (which is usually the case). I am the first to applaud any manufacturer … major brand or otherwise … that discloses the specific quality of the materials inside it and uses higher quality materials than their competitors because then you can make meaningful comparisons between mattresses in terms of quality and value.
Some of the larger brands are already more open and transparent than others (see this article) and do have some better quality and value mattresses … but unfortunately the largest manufacturers (the top 5) aren’t in this group. Since all the manufacturers have access to the same materials that they use in their mattresses … its just a matter of knowing how to make meaningful comparisons. The quality/durability of materials is quantifiable and in spite of the marketing that is rampant in the industry … there are simple ways that you can know the quality of a mattress regardless of the name of the manufacturer on the label. Being smaller or privately owned also doesn’t mean that you will find a good quality or value mattress because some of the smaller manufacturers also aren’t transparent and don’t make good quality or value mattresses. The key is always to make sure you are dealing with knowledgeable and transparent manufacturers or retailers that have the knowledge and the willingness to be able to tell you what is inside their mattress.
You can read more about about the major manufacturers, the current state of the industry, some of its recent history, and why I started the site in post #12 here and in post #404 here and post #4 here and in post #3 here as well as the articles on the main page of the site and here.
There are hundreds of sources of good quality and value mattresses all across the country and a few of them (currently about 30) are members of this site. If your wife believes that the members of this site are the only good quality and value choices available across the country then she is not correct because there are many. There is more about this in post #5 here.
While it’s true that not all foam is created equally and that the quality of the materials in a mattress is second to the suitability of a mattress … it’s also true that in terms of quality and durability that the density of memory foam and polyfoam is the single biggest factor in the durability of a foam regardless of the foam manufacturer. All the North American foam manufacturers make a range of foams from very low to very high quality and they are all closely comparable which is why they are so competitive. Mattress manufacturers of any size have the same or similar choices in terms of the foam manufacturers they choose to use to supply their materials and density comparisons across manufacturers is a meaningful comparison to compare the relative quality or durability of the materials in a mattress. You can read more about the factors that can affect the durability and useful life of a mattress in post #4 here.
I think the most important point is that these aren’t mutually exclusive and you can have both … if you know how to look and how to research a mattress. It’s also not realistic to expect a mattress that uses lower quality materials to last for 7 years and it’s also realistic to expect that a mattress that uses very high quality materials can last you longer than 9 years. There is a much bigger difference than you may realize. In addition to this you can also end up paying twice the cost for a mattress that is no more suitable for you (and perhaps less so) and won’t last nearly as long as another one that is just as suitable and the same or better quality at a significantly lower price.
Of course each person may have different criteria that are important to them as part of their personal value equation but to me as long as you know what you are buying, know how to make meaningful quality and value comparisons based on factual information rather than marketing hype, and you make a choice that is most suitable for you … then the site has done it’s job and I’m happy. The information you will need is available here but of course what each person does with it is up to them. At least you have accurate and factual information available to you and if you choose to follow the steps of the tutorial post you will have very high odds of making a great choice that will last you for a long time at a great price 
Phoenix