Hi sleepypeepy,
The first place to begin is the tutorial post here which has all the basic information, steps, and guidelines you will need to make the best possible choices.
The better options or possibilities I’m aware of in the Boston area are listed in post #2 here. You have some good options in the area including Spindle Mattress which is a member of this site which means that I believe they compete well with the best in the industry.
If you are comfortable with an online purchase the tutorial post also has a link to the members here that sell online. Brooklyn Bedding and Dreamfoam are sister companies and as Stepane mentioned both are members of this site as well and would also make great choices.
Phoenix