Hi soul4ever,
First to alleviate your concerns about latex as a general category of foam … any quality latex (latex made without fillers) is the most durable out of all the categories of foam (polyform, memory foam, and latex foam). It will far outlast any other foam although some of the better more expensive polyfoams (that you won’t typically see in mass market mattresses) can approach it. Of course any softer foam will have a shorter lifespan than a firmer version of the same foam but as a category and compared to any other foam … latex is more durable than any other foam in the same softness level.
Latex foam is made using 2 different methods … Talalay and Dunlop. Either of these methods can use various combinations of synthetic latex or natural latex. With Dunlop which is generally a denser material (and typically less “springy” and firmer) the 100% natural is the better and more durable choice IMO although blends with some degree of synthetic (I wouldn’t go any lower than 50%) can be a good choice for a slightly lower budget. With Talalay … because of various technical reasons that are connected with the cell structure of the foam and the difficulties of pouring low ILD natural talalay … the blended (a combination of synthetic and natural) version is more durable but this is particularly true in the softer foams and not so true in the denser foams that are used in the support layers or firmer comfort layers.
All of these are more durable choices than any other foams of a similar firmness level regardless of weight which is particularly important for those who are heavier. There’s more information about the various types of latex here.
A double sided latex mattresses would give the softer foam and fiber that is used in the comfort layers or quilting a “rest” when they were flipped and would extend the life of what is already a very durable material.
So yes … latex will give you a more durable mattress than any other foam and the increased durability would more than offset any increase in price IMO. In other words … it has more “value”.
Some of your more local factory direct options include …
http://www.verlo.com/ Peoria and others. Regional factory direct outlet. Each store is a franchisee and they are owned by Vymac (NOTE: now sold to Marcus Investments). They make a range of mattresses of all types and have some good quality and value.
Denver Mattress® - The Easiest Way to Get the Right Mattress Peoria, Springfield, Champaign, and others. You have already seen these and they are also a regional factory direct outlet that produce a range of mattresses of all types. I would focus on their own brands here because they also carry other major brands they don’t make themselves that I would avoid.
http://www.lebeda.com/locations.html Peoria, Champaign, Springfield and others. Another regional factory direct outlet that produces a range of mattresses including latex.
http://www.magicsleepmattress.com/ Marseilles. Local factory direct manufacturer. They make mainly polyfoam/innerspring mattresses and memory foam and their site doesn’t list any latex or latex hybrids (except a latex memory foam combination).
http://www.bendermattress.com/ Urbana, Danville. Local factory direct manufacturer. They also make a range of mattresses including latex.
If you are going to the Chicago area anyway … then IMO a visit to Quality Sleep Shop/My Green Mattress may be your best choice of all. Tim is great and very knowledgeable, helpful, and no pressure (what I call “mattress people”) and they build exceptional quality and value in their mattresses. Of course they are also a member here which means that I believe they compete well with the best in the industry in terms of their quality, value, service, knowledge, and transparency and the additional 5% discount for members of the forum doesn’t hurt either 
Phoenix