The Revivify Support Mattress is a good value mattress that should have wide appeal. Its non-toxic certifications are also noteworthy.
Mornington Medium Mattress
The Mornington Medium Mattress is a nice mattress that that includes a comfort guarantee and a non-toxic certification.
Rejuvenate 2.0 (Discontinued)
The Rejuvenate 2.0 Mattress available at the Original Mattress Factory has a nice amount of spring and offers a nice balance of comfort and support.