Hi dealio,
The first thing I would suggest is a little reading to give you a general sense of your options and a bit about matterials and construction.
I would start with the mattress shopping guidelines here.
Nest I would read through the overviews that are in the mattresses section of the site.
I wouldn’t “study” these but just absorb enough of them to give you a general sense of your choices and to be able to ak better questions. Once you’ve read them you will know more than many mattress sales people :).
As I mentioned in the guidelines, I would focus on local manufacturing or better sleep stores.
There is a list of these centered on Trenton, NJ in post #4 here and there is another similar list with a couple of other options centered in West Chester in post #2 here that should “cover you” on both sides.
With these choices … you should be able to find a mattress with much better value than either of the options you have listed (which IMO are both overpriced and not very good value).
If you have questions along the way feel free to post them.
Phoenix