Hi Inki,
I would keep in mind that there are 3 main types of foam and all of them are very different from each other. They are polyfoam, memory foam, and latex foam. The first place I would start your research is the tutorial post here which has all the basic information, steps, and guidelines you will need to make the most informed choices. Personal testing in local stores can give you a good sense of which types of materials (foam or otherwise) you tend to prefer but no matter which type of mattress you prefer it’s also important to make sure that the quality of the materials or the foam is good (especially in the comfort layers of the mattress) because this will be the most important factor in the durability and useful life of the mattress.
Some of the better options and possibilities I’m aware of in the Fort Myers / Cape Coral / Naples area are listed in post #2 here.
Phoenix