Hi Delia,
You’ve probably seen this but the better options I’m aware of in the NYC area are listed in post #2 here and there is a more descriptive and “categorized” description of most of them in post #4 here. I would focus on the last 5 in the second link (or the ones that are within reasonable driving distance) which for most people would probably represent their best value.
I think highly of the Berkely Ergonomics mattresses at Scott Jordan and a forum search on “Berkeley Ergonomics” (you can just click this) will bring up much more information and feedback about them. NOTE ADDED: Scott Jordan is now a member of this site as well
RoomandBoard also has some good options in a Dunlop latex mattress which also has a cotton cover quilted with wool that I would also consider to be good value.
You may also want to talk with Mark at Dixie Foam on the phone and/or pay them a visit as well.
When you are testing mattress locally … IFD (or ILD) information has nothing to do with quality and your body and personal testing will tell you much more than any comfort specs anyway so comfort specs are not so important for a local purchase. It’s always the “quality specs” that are the most important information you need because you can’t feel quality in a showroom. Both of these use good quality materials though and there are no “weak links” in either choice.
“Bang for your buck” has many different meanings for different people.
In terms of layering suggestions there is no formula that can turn each person’s weight and height and sleeping positions onto a specific design because there are just too many variables involved and there are many different designs that may work equally well. I’m happy to provide more generic information about the theory behind different layering options and designs (which you will find in the mattresses section of the site in the pages about different body types, sleeping positions, and layering designs) … but I leave the specific suggestions to your more detailed discussions with each manufacturer who will suggest the options they have available that they believe best matches your needs and preferences based on your body type and sleeping positions as well as any local testing you may have done and any other information you can provide them. They are much more familiar with the specifics and small details of all the materials and components they use and how they all interact together and with different people and because of the differences between each manufacturer’s designs … each online manufacturer may give you a different suggestion based on their experience with their own design and the “averages” based on their customers experiences.
Each manufacturer will generally have two or three standardized suggestions (or in some cases more) that will fit most people which they generally choose between and to get more specific than that would require a more extended conversation with each manufacturer you are working with. It’s very easy to get over-involved with specifications but its much easier and more effective to let each manufacturer use their knowledge and experience to help you make the best choices between what they have available. In other words … they already know, especially when it comes to their own designs, what you would otherwise have to learn.
I would avoid the Foam factory (or foam by mail or any of their other multiple sites) completely. You can read more about the reasons why in post #2 here and post #2 here (as well as many other posts on the forum including some very recent ones which a search on “FBM” will bring up). Quite frankly … I don’t believe they are even selling Talalay latex.
There is a big difference between ordering online and ordering locally where you can test a mattress before you buy it. Of course many of the better online manufacturers also have great value and some offer various layer exchanges or other options that can reduce the risk of an online purchase. I normally consider a 20% difference between an online purchase and a similar local purchase to be roughly equivalent “value” but of course each person has a different risk tolerance and may have a different number based on their own personal “value equation”. The online manufacturers that are members of this site and sell latex mattresses are listed in post #21 here. I would talk with each one that interests you, narrow your choice down to the “best” option at each manufacturer or retailer you are considering (both local and online), and then one by one go through the most difficult part of all which is eliminating some great options that are among the best in the country until you are down to one.
When you have eliminated all the worst options (such as major manufacturers and chain stores which you have) and have final choices that are all choices between “good and good” … then all the objective, subjective, and intangible differences between each mattress, merchant, and the options they have available both before and after a purchase that are more or less important to you are the way to choose between them rather than thinking in terms of better or worse. In the end it’s always about what is best for you (and nobody else can know or decide this for you) and at this stage it would be difficult to make a quality or value mistake. No matter which direction you go, you will have a mattress that is higher quality and better value than the vast majority of consumers will ever buy 
Phoenix