Hey there Deltaxdog,
Welcome to the MattressUnderGround. We are happy to have you as a new MUGster (subscriber) to our community and thank you for your question.
While TP may excel in their class of MF mattresses and sell a substantial quantity, returns and exchanges at most places can prove to be quite costly.
Tempurpedic, is like many other “marketing” brand’s materials, like those who incorporate elements such as gels and grids. TP is likely the best in its class. It boasts unique characteristics and a specific feel that may either appeal to you or not.
I have a dozen of their pillows, which I write and speak highly of them quite often, but their mattresses have found to be uncomfortable, sinking, hot, like being swallowed by quick sand.
Every time we have looked for a new mattress, we have given a TP, but never they never make it into any final potential choice, no matter how they have changed the formula they use in their foam.
Starts off firm (which is great), then you sink and get trapped if not cooked.
It is one of the best-selling mattresses, so people are buying them and are either loving them or dealing with them as returning or exchanging one can sometimes prove costly.
It would seem as a couple with dissimilar body profiles you may need individualized comfort.
If you really love memory foam then you may want to look at the tempflow line of mattresses as they are one as seen here that directly competes with Tempurpedic. They are not a budget version, quite the opposite, a high quality version with designs that employ advanced air channeling and foster more airflow and and an attempt to allow you to sleep less hot. Plus offer split comfort designs as part of their options. Just as tempurpedic uses over 5lb+ memory foam, tempflow is built with MF that falls into that same range.
Of course there are other options, for example @DLX just introducted their MemoryMax Hybrid. A very high quality engineered mattress combining memory foam and HD foam into their comfort section of the mattress for folks who love the feel of memory foam, but want the added strength of durability, support and longevity. @EngineeredSleep is another that comes to mind that offers a memory foam hybrid in their Duo Memory foam mattress.
Despite advertising and marketing claims, there are viable alternatives available. While TP may assert that their mattresses cannot be replicated due to their secret formulas, the same argument could potentially apply to nearly any other mattress, even those that disclose their exact specifications.
You could search online for 5lb viscoelastic memory foam and find variations from super soft to extremely firm. This shows how descriptions alone can’t guarantee an exact duplication of any foam layer.
When it comes to affordability versus costliness, @BillyIdol underscores a crucial point. Similar to comfort, the price tag and its alignment with an individual’s budgetary perspective are purely a “selective valuation,” requiring the evaluator themselves to determine.
While Tempurpedic mattresses have their strengths, including unique materials and brand recognition, many users find issues with sinking and heat retention. Exploring alternatives such as Tempflow for improved airflow and customizable comfort, or other brands offering memory foam hybrids, may provide better options tailored to individual preferences and budget considerations.
Hopefully this helps bring an additional perspective for you to move forward in your search and bring your wife back to your side of the financial aspect of the conversation 
Best of luck,
Maverick