Hi Jameslmyers3,
Just in case you haven’t read it yet … the first place I would start is post #1 here which has all the basic information, steps, and guidelines you will need to make the best possible choices.
Some of the better options and possibilities in the New York City area are in post #2 here and there is a more categorized list with more detailed descriptions of many of them in post #7 here.
I would keep in mind that memory foam (gel or otherwise) can tend to sleep warmer than other types of mattresses and I would be cautious about assuming that a gel memory foam will sleep cooler over the full course of the night. You can read a little more about all the many factors that can affect the sleeping temperature of a mattress in post #2 here and there is more information about gel foams (including gel memory foams) in post #2 here and the posts it links to.
The “read first” post also links to some mattress shopping guidelines which suggest avoiding chain stores and major brands (such as Sleepys and the Sealy Optimum you are considering). In terms of quality and value … a mattress is only as good as its construction and the quality of the materials inside it and most major brands either don’t disclose this or use lower quality materials than many smaller independent local or regional manufacturers.
You can read a little more about the Optimum line in post #48 here.
You can also read more about Bob’s Discount Furniture (mybobs.com) in post #4 here.
Without knowing the specific details of the materials in a mattress there is no way to make a meaningful assessment of a mattress or make an informed buying decision and I personally would stick with retailers or manufacturers that are more knowledgeable about their mattresses.
Some of the better options in the NYC area are listed in post #2 here and there is a more categorized list with some more detailed descriptions of some of these in post #7 here.
Phoenix