Hi Mattress Facts,
The outer “wrap” is called the ticking but most people just call it the cover. I’m not so sure that I would generalize the way you have because each manufacturer will choose or make a cover that is part of the design goal of the mattress. Specialty foams such as latex and memory foam will often have a looser cover so that the “feel” of the foam underneath comes through more but there are also many manufacturers (small and large) that use various types of quilting in their covers (ranging from polyfoam to wool to synthetic fibers) and many of them will tuft their top layers in some designs as well both of which will make the surface tension tighter. Some smaller manufacturers still have a quilting machine and make their own quilted covers and can design their own quilting pattern (quilting patterns that are tighter make a firmer surface).
For some reason I didn’t notice that you had posted your zip code in an earlier post. Some of the better options and possibilities I’m aware of in the Palm Beach area are listed in post #2 here and there is a list in post #2 here centered on Ft Lauderdale which is mostly duplicate but also includes some options in Miami and has a link to a thread with feedback about some of them.
Royal-Pedic are very high quality mattresses (you can tell this by their materials and construction) like other similar latex mattresses but they also have a premium price compared to other mattresses that use similar materials and are not particularly good value IMO. Of course “value” has many components and one of these is the suitability of a mattress or what I call PPP (Posture and alignment, Pressure relief, and Personal preferences) and if they are somehow “perfect” in every way and for some reason there was no other latex mattress that was even close then for some people their “value” may be based more exclusively on how they feel and perform rather than how they compare to other mattresses in terms of cost, construction, and the quality of their materials.
There is more information about dust mites in post #2 here and two of the main keys to controlling them are the ventilation of the mattress and the use of a good mattress protector (or in some cases where dust mite allergies are more severe a mattress enclosure).
Phoenix