Hi Tom,
One of the funniest experiences that can happen when someone knows some “mattress information” is the reactions and blank looks you get when you ask “different” questions from the norm in many of the massd market outlets or chain stores who are trained to tell stories more than they are to provide meaningful information.
The Serta Pure Response Splendor Plush is one of the relatively “better” values in a major brand but they missed the boat when they started adding polyfoam in the layers above the latex core (1" comfort foam, at least another inch and likely more of convolute polyfoam, and then the synthetic fiber which will all tend to compression set and breakdown over time). One of the clues that you can see when manufacturers do this is that their warranty exclusion is 1.5" instead of a typical latex “exclusion” of .75". In other words … the Pure Response line and the Vera Wang line by Serta has too much polyfoam in the comfort layers although they are closer than some other brands (like Dr Breus) which many outlets call a latex mattress when the highest end model only has about 50% latex in it and the lower models much less. The second problem with this mattress … besides that what you feel is a combination of soft cheap polyfoam mixed in with the latex is that the specs of the latex layers themselves are not provided so they are of little use for using as a blueprint. The Simmons Natural Care Elite (not the Natural Care) is another major brand mattress that actually doesn’t use the polyfoam at all so in this case the construction is great but the price puts it out of the value range (unless it is deeply discounted or clearance since it has been out for some time). At least they do provide the specs for this mattress so it can be meaningfully compared with other options. In other words … the major brands usually either “cheap out” on their materials and construction or they inflate their price on the better materials and constructions.
There are so many variables in terms of layering that fits each person individually that only actual testing can determine the exact layering that is best for an individual. There are however some general guidelines that are very useful starting points and there are some suggestions in post # 4 here and Post #4 here in terms of the layer thicknesses and softness of comfort layers that are good starting points. There are also some guidelines in the mattresses section of the site about different sleeping positions, and different weights and body shapes.
The biggest challenge between the two of you will be your wife’s combination side/stomach sleeping which is the most difficult combination of all. Stomach sleeping in general needs a thinner firmer comfort layer and firm support to prevent sleeping in a swayback position and straining the lower back. Testing for pressure relief on her side and then testing for alignment separately on her stomach (making sure her hips don’t sink in too far) will be important for her.
In your case … the biggest issue for many men is making sure that the comfort layers are thick enough and soft enough for the lighter wider shoulders (relative to the weight and width of the hips) to sink in far enough on your side to align with your hips. Shoulders that don’t sink in far enough can lead to pressure issues in the shoulder and arms (tingling or falling asleep) or to alignment issues in the upper back (the upper torso not coming to rest in alignment with the lower pelvis).
The most helpful testing is to test each mattress separately for pressure relief and then for alignment without “mixing up” the two or confusing them with subjective feelings of overall comfort.
While there is differences between having two pieces under the comfort layer vs one … both can have value depending on what someone is trying to accomplish.
If a mattress has a support core of 3" of 28 ILD over 3" of 36 ILD … and then a 3" comfort layer of 19 ILD above it, this would be a “progressive” contruction and the middle layer would in effect “help” the comfort layer to “act” a little softer and thicker than if it had a firmer 6" core of 36 ILD. With a single 6" core of 28 ILD instead … the cradle formed by the comfort layer would be slightly shallower than the 3 layer construction but the hips would sink down slightly more. While some of this seems counterintuitive … each layer either “allows” or “prevents” other layers from compressing more or less deeply. This is what I have called “order of compression” and some examples of testing that show this in action in real life are in post #10 and 11 here.
Phoenix