Hi javaqueen601,
Welcome to the Mattress Forum! 
The first place to start your research is the mattress shopping tutorial here which has all the basic information, steps, and guidelines that can help you make the best possible choices … and know how and why to avoid the worst ones (including any major brands such as Simmons or any mattress where you aren’t able to find out the quality of the materials inside it and identify any weak links in the mattress).
You can also see my thoughts about airbeds in this article and I would tend to avoid them unless there was a compelling reason to consider it over all the other options you have available.
The tutorial post also has some testing guidelines that can help you choose a mattress that is a good match for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) because every manufacturer makes mattresses that are both softer and firmer.
There is also more about the most important parts of the “value” of a mattress in post #13 here.
As you can see … outside of PPP, a mattress is only as good as its construction and the quality of the materials inside it regardless of the name of the manufacturer on the label (which is relatively unimportant) so it’s always important to make sure you can find out the quality of all the layers and components inside any mattress you are considering (see this article) so you can identify any weak links in the mattress and make more meaningful comparisons with other mattresses. Without this information it’s not possible to be able to assess the quality or durability of a mattress and you would be making a blind purchase which is a very risky choice and one of the biggest reasons for buyers remorse much too quickly after a purchase.
VI Spring is a very high quality and “ultra premium” mattress but it’s also in an ultra premium price range which certainly isn’t necessary to find a mattress that is both suitable for you in terms of PPP and durable in terms of the quality of the materials. There is more about ultra premium mattresses in post #2 here and post #2 here.
The better options or possibilities I’m aware of in the Denver area (subject to the “value” guidelines I linked earlier) are listed in post #2 here. You have some good options available in the area.
In simple terms … your research will come down to …
- Careful testing for suitability (PPP).
- Checking the quality of the materials inside a mattress for durability and to make sure there are no weak links or lower quality materials.
- Comparing your finalists for “value” based on all the parts of your personal value equation that are most important to you.
Phoenix