Hi princejci,
The first place I would start your research is post #1 here which has all the basic information, steps, and guidelines you will need to make the best possible choices … and avoid the worst ones including all the major brands such as Sealy.
You can read a little more about the Sealy Optimum matresses in post #48 here but in general … like all the major brands … they are lower quality/value than many other mattresses made by smaller manufacturers in the same budget range.
Some of the better options in the Grand Rapids area I’m aware of are listed in post #273 here.
Phoenix