Your older plush Simmons Beautyrest held up well, because it had no memory foam in it.
Since you bought yours, Simmons has been sold to an investment group.
And since then, memory foam has been added to the upholstery layers.
As of June 2017, all of the upholstery is memory foam.
The purpose of using memory foam is to cause their mattresses to need frequent replacing.
The diabolical part of memory foam is that it returns to it's original shape...or close enough to it, so that you will not prevail in a warranty claim.
This, despite that the memory foam quickly loses the little resiliency it originally has...losing it's comfort and support.
All this, for the sake of maximizing profits...selling more mattresses, more frequently, to the same people.
In short, nothing they make today comes close to the quality of the one you have.
This mattress I'm recommending to you, is the same one we sleep on at home.
It is very much like an old Simmons Beautyrest, with the same pre-compressed individually pocketed coil system.
The quality, however, is far greater than anything Simmons makes today.
Quite frankly, at your age and physical condition, it should be the last mattress you'll ever need to buy.
The coils, while made the same as Simmons, are stronger and much more resilient...made of twice tempered steel.
(The coils in the Simmons Beautyrests are not tempered)
The upholstery is natural Talalay latex, which has been the best upholstery used since the 1920s....Containing NO Memory Foam.
The components are of very high quality....resulting a very long lasting mattress.
There are 5 choices of comfort. All provide firm support, with the Plush Eurotop being the most comfortable of them.
Based on what you've told me, you should be happy with the Ultra Plush model.
Due to the high quality of the components, all are firmer than they sound.
The brand is Natura of Canada....their Greenspring line.
Here is a link to those mattresses.
Greenspring Liberty Plush Euro Top. Experience deeper, more restorative sleep with the Liberty Plush Euro Mattress. Lush helpings of natural ingredients come together ...
Delivery is Free and there's NO SALES TAX
Factory Direct to You....
All Items Made Factory Fresh to Fill Your Order
Free Delivery Nationwide....NO SALES TAX.