Hi passim,
If I was in your shoes and you can I would be tempted to cancel the order and give yourself some time to do some more extensive research first so you an find a mattress that is a better value or perhaps a more suitable choice than what you ordered. You will be sleeping on any mattress you buy for a long time and a mattress is one of the most important purchases you can make because it will have a bigger effect on how well you sleep and your overall wellbeing than almost anything else so it makes sense to make a choice that is the best match for all the criteria that are important to you.
The first place I would start is the tutorial post here which has all the basic information, steps, and guidelines that you will need to make the best possible choices … and know how and why to avoid the worst ones. The tutorial also includes a list of the better online manufacturers and retailers I’m aware of that sell memory foam mattresses and many of them make mattresses that are close approximations of the Tempurpedic line but in much better price ranges.
While I don’t think that gel memory foam is “complete hype” … it’s true that the benefits of gel are often exaggerated. There is more about the different types of gel materials and gel memory foam in post #2 here and much more detailed information in post #2 here and the posts it links to.
There is also more about all the many variables that can affect sleeping temperature in post #2 here and the posts it links to so if sleeping temperature is a major consideration for you it can help you choose materials that tend to sleep cooler. In many cases the mattress protector and the type of sheets you use can also make a significant difference in sleeping temperature regardless of the type of mattress you choose.
If you let me know the city in Colorado you live in or your zip code I’d also be happy to let you know about the better options or possibilities I’m aware of in your area.
Phoenix