Good Morning Joe,
There isn't a name brand mattress, made today, that will long withstand the weight of average size people...let alone, a man your size.
Brands that you once could rely upon for quality, have all been sold to investors who are now making high profit/low quality mattresses.
I have a couple of options for you.
Options #1) The Wolf Old Fashioned Two Sided Mattress in Firm
This is the reasonably priced option, but still, far better quality than any Simmons mattress.
This mattress uses the same type of coil system as is in the Simmons Beautyrest.
The steel, from which the coils are made, is twice tempered.
Simmons uses raw steel...not tempered, at all.
The upholstery is Natural Plant Bases Polyurethane Foam, which is far more resilient than the memory foam used in all of the Simmons Beautyrest mattresses.
Add a Suite Sleep 2" Medium Soft Organic Latex Topper to it for surface comfort and added Longevity.
While quite a bit better than what you have, option #2 is your best option for long term use.
The Natura of Canada Greenspring in Firm and a Suite Sleep 2" Medium Soft Organic Latex Topper.
This mattress, also uses a double tempered pocketed coil unit with latex upholstery.
The coil count is higher and the latex is more resilient than the poly foam in the Wolf mattress.
This particular model is very firm...too firm to sleep on comfortably.
The latex topper will do two things...provide the surface comfort you and your wife need to sleep deeply, and prevent the mattress from wearing by absorbing much of your body weight.
Latex is and has been the best upholstery material for the last 100 years.
High quality, Pure Latex lasts for years.
So as the years go by, you should only need to replace the topper from time to time.
Since there is a substantial difference in weight between you and your wife, it will be imperative that you rotate your new mattress regularly to attain more even wear, which will extend the comfort life of the bed....once a month.
If the mattress is a king size, I suggest a quarter turn rotation.
Only a king is square enough to pull this off.
The quarter turn rotation will enhance the even wear of the mattress.
Option #1 arrives via UPS
Option #2 comes with white glove delivery, which includes set-up and removal of all packing materials.
Either way, Delivery is FREE and there's NO Sales Tax.