Hi mattressnovice,
Have you had the chance to read the tutorial post ? It has all the basic information, steps, and guidelines that can help you make the best possible choices … and know how to avoid the worse ones (including the major manufacturers such as Serta).
If you are comfortable with an online purchase it also has a link to a list of some of the better online options I’m aware of.
It also includes some testing guidelines you can use to decide which mattress is the best “match” for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences).
As you will read … outside of your personal testing a mattress is only as good as its construction and the quality of the materials inside it and I would make sure you know the specifics of what is inside any mattress you are considering and use the guidelines in the tutorial post to make sure it has no “weak links” and that you can make more meaningful comparisons to other mattresses.
I’m assuming you are in the New York city area so just in case you haven’t seen it some of the better options and possibilities I’m aware of in the area are listed in post #2 here and there is a more categorized list with some more detailed descriptions of some of them in post #7 here.
Out of the three you mentioned …
The Dreambed Deluxe uses good quality materials and there are no “weak links” in the mattress (Dixie foam is transparent and will provide you with the density of all the foam they use). NOTE ADDED: They are now a member of this site as well
You can see the specifications of Summerfield Fusion Heather Plush Firm here and as you can see it uses more than “about an inch or so” of lower density foams in the upper layers (1.2 and 1.5 lb polyfoam and 3 lb memory foam) which is more than I would suggest (see the guidelines here).
You can see more information about some of the iComfort lineup (including the Savant) in post #11 here but as you can also see in the guidelines I would avoid the major brands because they either tend to use lower quality materials or are not very good “value” compared to many other mattresses in the same budget ranges.
Any foam mattress and most pocket coil mattress that use good quality/density materials would be fine with raising the head of the mattress by 6" or even for use on an adjustable bed which can raise it even more.
If you follow the steps in the tutorial post one by one you will have the best chance of making the most suitable and best value purchase possible.
I would also keep in mind that one of the most important parts of a mattress purchase is how well it matches your body type and sleeping style in terms of PPP so I would make sure you do some careful and objective testing on any local mattress you are considering because no matter what the quality or value of a mattress … if it isn’t suitable for you to sleep on it would have little value to you.
Phoenix