What makes the Simmons Beautyrest so comfortable, is the individually pocketed coils...all moving independently from one another.
They contour to the shape of your body and maintain the spine's natural alignment.
The coils are pre-compressed, (a 9" coil in a 7" pocket), which pushes back against the spine...for much better support than your foam mattress.
Unfortunately, they don't hold up very well. Between the coils not being made of tempered steel and the memory foam upholstery, they are mattresses made to need frequent replacing. Under your weight, you'd be lucky to get a couple of years out of one.
What I'm recommending is made by Natura of Canada...specifically, their Greenspring line.
These mattresses use the same pre-compressed individually pocketed coils that Simmons uses....for the support you liked so much.
The difference between the two brands is dramatic.
The coil count is higher.
The steel, from which the coils are made, is double tempered.
The primary upholster is natural Talalay latex....containing NO Memory Foam.
I'm 66 years old with lots of disc related back problems. My wife and I have their ultra plush model.
It provides excellent support and comfort...surface comfort that doesn't allow you to sink, and doesn't sleep hot.
The feel that latex produces, is one of 'floating'. It's, really, quite nice.
We live without back pain. And with each of us in the 225 lb range, the mattress remains in like new condition after more than 3 years...no sign of wear.
Here is a link to those mattresses. There are 4 choices of comfort.
The Liberta Firm Mattress delivers improved well being and scrumptious comfort with eco-friendly flair. A layer of NaturaWool™ maintains temperature control and gently buffers pressure points to diminish nighttime tossing and turning.
White Glove delivery is free and there's no sales tax.