Hi Mandy1022,
Welcome to the Mattress UnderGround, we are happy you have posted your question here.
As someone who used to be 6 feet tall and over 250 pounds myself, I completely understand where you’re coming from. Even though I’m around 220 now, the mattress-buying approach for higher-weight sleepers stays the same. The two most important things to focus on are a supportive and durable support layer inside the mattress and a rigid, non-flexing foundation underneath it. If either one is weak, you can run into sagging or back issues much sooner than you’d expect. Given your sizes, sleep positions, and different firmness preferences, it makes sense that mediums have been the closest match so far.
Stearns and Foster and Beautyrest Black can feel great at first, but their pillow tops tend to soften faster under heavier weight, so if you’re not sold already (which is probably best), that’s a good sign to keep exploring.
The Brooklyn Bedding Titan Plus Luxe is a solid option because of its stronger coil system, although it still has some of that modern foam-hybrid character, which may or may not suit you since you don’t love memory foam. I happened to be at the Las Vegas Market when BB introduced the Titan Plus Elite, which I personally found to be an excellent mattress, so much so that I bought one for my guest room. My wife and I sleep on the Brooklyn Bedding Plank Luxe, which is a very firm mattress, and despite her 5’4", 135 lb frame, and mostly side-sleeping habits (I call this against-the-rule sleeping), we both love it. The Elite version uses the same 13.5g coil system, although in the Elite they are 8" versus the Plank Luxe at 6". The Plank Luxe is a two-sided mattress, so the shorter coil makes sense. It also incorporates microcoil construction in the comfort layer, which helps keep you cooler when sleeping as it allows for better air flow. And it’s cushier luxury firm eurotop style cover is great for when you sleep on the side while still maintaining a firm support layer for stomach sleeping.
Since you both sleep on your stomach at times, it is very important that your support layer does not allow you to sink into the mattress, so staying with a very robust support spring layer, firm latex, or high-density firm polyfoam is going to be key. As you explore, you may want to consider mattresses that allow for split internal feel or configurations.
I would urge you to look at @CST website, @FloBeds for very customizable Talalay Latex configurations that this type of latex can be crafted into. Manufacturers like @Sleep_EZ and @Arizona_Premium can craft you a hybrid or all-latex combination as well. For more traditional mattress crafting, Gardner and Sigma in Massachusetts can design almost anything you like, and if you are close enough, you can test them in person. Keep in mind that testing in person is important, but not as important as the real test, which is in your home environment over a longer period of time, say a month or so, to truly become familiar with your mattress setup.
Since you have already considered something like the Titan Mattress, there are several mattresses that come to mind in that genre that are quite good. @DLX offers their Premier Hybrid and LatexLux. Both rest on the same core base, but in a queen or king can be designed with an internal comfort layer to firm up your husband’s preference while providing the cushion you prefer, without causing you to sink into the mattress the way you likely would with viscoelastic memory foam in the comfort layer. This is where thoughtful construction of both the mattress and foundation plays an important role. @EngineeredSleep has their own take on splitting comfort for each sleeper, and both DLX and ES provide excellent long-term swapping options, which means you may not need to replace entire mattresses down the road.
Additionally, when we circle back to the Titan category, 3z’s Helix Elite line may be a better choice if you need to customize. @yawnder offers the Helix Plus Elite, which features the same spring support layer as the Titan Series, but as an authorized dealer that ships nationwide, they can offer a split internal king, maintaining the firm feel your husband prefers while stepping it down on your side for a bit more cushion and softness. Although, having tested this mattress and loved it, you may be very happy with this in it’s original design, as the cover/panel has a softer landing than something like the Titan Plus or Helix Plus core mattress.
Fortunately, you have a lot of choices to satisfy your needs. You can choose from very customized offerings to made-to-order options shipped nationwide with quality components.
Overall, for both of you, durability and proper support should be top priorities, and a well-constructed hybrid or latex mattress paired with a rigid foundation will usually outperform most pillow tops over time. When it comes to pillow tops, you should be very choosy; brands like Shifman and ViSpring are in a whole different category with their pillow tops. For you, leaning toward a topper to finalize comfort may be a better solution than a standard pillow top.
Hopefully, this gives you a little insight into what is available and some sensible options in your search.
Maverick