Hi mrsbad,
Just in case you haven’t read it (and from your comments you seem to have read at least some of the information it links to) … the first place I would start is post #1 here.
Out of the mattresses you are mentioning … I would eliminate the Serta (you probably won’t be able to find out the quality of the materials and if you do it will likely only make it clear that the quality/value isn’t good anyway) and would focus on the Bowles you are mentioning along with any other possibilities in your area (if you let me know your city or zip I’d be happy to let you know of any possibilities in your area I’m aware of).
A mattress is always a combination of softness on top and firmness in the deeper layers rather than one or the other or a “blended” rating such as firm or medium firm (which has little meaning). The comfort layers on top are primarily responsible for your “comfort” or pressure relief (such as relieving pressure or discomfort on your hips and shoulders) and the deeper layers are primarily responsible for your support and alignment. sometimes there are middle or “transition” layers that perform a bit of both functions. In other words … a mattress has two main functions and while they are related … each one may need its own level of softness, firmness or thickness that is suitable for you. This is why a “single” rating can be misleading. It’s also a good idea to test for each of these independently rather than going by the “overall feel” of a mattress.
Bowles Lady Americana Gold Box Top
Box Top Pillowtop with fabric quilted to 1 1/2" foam: This is likely 1.5 lb polyfoam which is in the range of a polyfoam quilting layer that I would normally consider to be OK (around an inch or so) but is edging towards a little much. This is thin enough though that it’s softening won’t have a significant effect on the mattress.
VLS Visco Lumbar Support box top insert: This is a layer of higher density memory foam they put in the center third for additional Lumbar support. This too should be fine.
1" Firmer Talalay Latex boxtop insert: This is a high quality material.
2 1/2" Micro Coil box top insert: This would also be a durable component.
2" Talalay Latex: Once again this is a high quality material.
704 Marshall “Zoned” “Pocketed” Foam Encased Coil w/ 3" x 6" High Density Firm Encasement Rails: This is also a good component and the innersprings wouldn’t normally be the weak link of a mattress anyway. Depending on the density of the polyfoam surround … it may soften over time if you tend to sit on the side of your mattress. I would want to know the density of this foam.
Overall … these are mostly good quality materials with just a very few potential “weak links” (the quilting polyfoam and the foam surround) but these are not that significant.
G-700:
Outlast® fabric quilted to 1 1/2" foam: Same comments as previously.
2" gel infused memory foam: I would want to know the details of this layer (density and type of gel memory foam). It will likely soften more than the Talalay latex in the other mattress.
2 1/2" micro coil insert: Same comments as previously.
VLS visco lumbar support: Same comments as previously
1" firm foam: This is polyfoam and I would want to know the density of this layer. Normally knowing the density of only an inch of firm polyfoam is not an issue but there is already 1.5" in the top layer so I would want to know this as well because the softening of the top layer in addition to the softening of this layer would have a slightly more cumulative effect (which would be slower because it’s deeper in the mattress) than just a single layer alone but this layer probably wouldn’t be a major factor either.
704 Marshall “Zoned” “Pocketed” Foam Encased Coil w/ 3" x 6" High Density Firm Encasement Rails: Same comments as previously.
I would tend to avoid this unless the mattress was particularly suitable (or designed) for this type of combination (or unless it was needed for fine tuning). Even firm mattresses often have some soft foam on top and putting a softer topper on this may give you a comfort layer that was too soft and thick or it could put the softer top foam deeper inside your sleeping system and could turn the soft foam in your mattress that was meant for comfort into a transition or support layer and it wouldn’t be as suitable for this. This can be a good idea in certain circumstances or when there are no other good alternatives but you would have to choose the base mattress very carefully and it adds some uncertainty into the picture even though the concept itself … when the combination is well designed … can have some real advantages but I wouldn’t choose this at the expense of a mattress that already used more durable materials and that you had tested for good pressure relief and support.
Overall in terms of quality and durability the Gold Box Top would likely have the most durable materials with the least possibility of softening or degrading (although I would want to know the details of the gel memory foam). Of course this has nothing to do with how well each mattress provides you with the PPP (Pressure relief, Comfort and alignment, and Personal preferences) that you need which is where your personal testing is so important. There is also a matter of preference here which would play a large role with the gel memory foam providing a lower resilience and slower response surface feel and the latex providing a more highly resilient and more faster response sleeping surface (even though both would be modified by the quilting polyfoam above it). There may be a difference between them in your “freedom of movement” when you change positions or move during the course of the night although neither is likely to “trap” you in the mattress.
In general … Bowles and Lady Americana will have better quality/value than most mainstream mattresses and both could make a better quality/value choice than most people would otherwise make and are probably among the better local value in the area.
Don’t forget that a mattress is not designed for sitting and how well it performs for this (where the weight is much more concentrated than when you are lying down) would not normally be all that significant a factor in a choice unless this was particularly important to you and it was a “deal breaker”.
Hopefully this will help you with how to choose between them (and again I would eliminate the Serta). Once you have decided on your “best” option at Bowles … you may also want to consider comparing the Bowles to a few of the other good options in the area just as a point of reference and to confirm that they really do have the best PPP, quality, and value available to you.
Phoenix