Hi typesomethingwitty,
Thank you … it always feels good to hear it 
This approach would only be worthwhile IMO if an outlet had both an ultra firm mattress and a topper in the same location so that you could test them together. If one has to be bought separately … there would be no way to test them together until after you had bought it so it would make more sense to buy them both online because your options are much greater and the value would be better.
There are several ways to get to an “ultra firm” mattress with an innerspring which is what you would be looking for. Some involve an ultra firm innerspring with softer foam on top which would be called “ultra firm” because the foam is soft enough that a person would feel the firmness of the innersprings. Another way to get there would involve less firm innersprings but firmer foam on top so that the “ultra firm” feeling came from a combination of both the springs and the foam. The better option would be to choose a mattress with the “firm foam” approach with as thin a layer of firmer foam as possible) as the firmer foam would act as a “transition” between the memory foam and the innersprings.
These are very hard to find because a mattress that is suitable for a base layer would be firmer than most people would even consider buying and may still have more foam of the wrong type or firmness to be “ideal” for the mattress and topper approach. I would use this as a way to buy locally if an outlet had the “ingredients” and if actual testing of a mattress vs. an online purchase was a very strong preference even if it was significantly more expensive than other options. The goal would be to find an ultra firm that preferably had 2" of less of firmer foam (which would become the transition layer). A little more (say 3" of firm foam) would move it away further from the ideal but may still be worth considering. Many manufacturers make a mattress like this but because they are like sleeping on a rock … not a lot of stores may carry them. It is easier to find a mattress like this by asking about construction (do you have an ultra firm innerspring mattress with 2" or less of polyfoam in it that feels like a rock) than by asking for a “name brand” because major brands tend to have many different names for the same mattress (in some cases several dozen).
A similar option that may have more benefits, fewer disadvantages (less unwanted foam) and better value and would give you a more traditional memory foam mattress would be buying a mattress that has removeable and exchangeable layers inside a zip cover. With a mattress like this … there is no unwanted foam and the top layers are just as replaceable as a topper (unzip the cover, replace the layer, zip the cover back up). These type of “choose your own layers” are very popular but they are more common with latex than with memory foam. They also use polyfoam support cores rather than innersprings (like most memory foam mattresses including Tempurpedic and others). The “buy a firm innerspring mattress and a topper” approach would give you a “hybrid” mattress and would be great if you had a preference for the feel of memory foam over an innerspring rather than a more traditional memory foam mattress. Otherwise … memory foam tends to do better with a foam support base. Post #5 in this thread which I just posted earlier today includes some links to some very good options with customizable memory foam mattresses.
[quote]More so than buying a mattress that is uncomfortable (“uncomfortable” has no meaning to me…I have been sleeping on a 35-year-old coil mattress!), my worry is buying a mattress that wears out prematurely (due to my weight or any other reason). Because of that, I’ll eliminate Enso’s mattresses and the iComforts from my list.
Does latex have an equivalent “5lb memory foam density” requirement I should look for, if we test latex and decided we like them?[/quote]
There are 3 “good” types of latex which are all exceptionally durable and would make good choices. The first is made with a process called the Talalay process and uses raw materials that are partly natural latex (NR or natural rubber) and partly synthetic latex (SBR). This is called blended Talalay. Talalay can also be made with all natural latex (no synthetic) and this too is very high quality. Finally there is a second less costly process called Dunlop which is a denser version of latex which is less “lively”, less consistent in it’s surface softness, and comes in fewer softness options (none of which are as soft as the softest talalay). Good quality Dunlop is also exceptionally durable and high quality but in this case I would only consider 100% natural Dunlop and would tend to avoid blended Dunlop. There is more about this in the article here. As the article mentions … the only one of these three that I would hesitate with in terms of durability is 100% natural Talalay in the softest ILD’s (below about 20 ILD). I wouldn’t hesitate to use all other softness levels in any of these three types (NR or blended Talalay or NR Dunlop) and all of them are more durable than even high quality memory foam.
There are 5 manufacturing members of this site that specialize in latex mattresses that either offer a choice of comfort layers or that are “choose your own layer” types of mattresses. Post #21 here has a list and brief description of them if you decide to go in the latex direction instead of memory foam.
Yes … this would be a good reason for most people to avoid it. Typical mattresses sales outlets today cater to the temporary and managed showroom feel of “comfort” rather than pressure relief, support, and preferences tailored to an individual. Their goal is usually to sell you more foam (meaning higher prices and more profit) with a story attached to justify the price rather than a more suitable mattress. There are always exceptions and there may be a few that do well with layers of memory foam that thick but in general mattresses that are bought strictly for comfort and with the idea that thicker is better will only feel comfortable for the shorter term and in the longer term will likely have issues with alignment/support and the premature breakdown of the mattress.
Side sleepers actually need the thickest (plushest) comfort layers because there are more “bony protrusions” such as hips, the pelvic crest, and shoulders that need pressure relief and the “gaps” in the side sleeping profile that need filling in are bigger. Back sleeping needs thinner comfort layers (less plush) and stomach sleeping needs the firmest and thinnest comfort5 layers of all. There is an article here with some guidelines for different weights and an article here with some guidelines for different sleeping positions.
[quote]At this point, I am liking the 1) ultra-firm mattress and add high quality 3" topper idea and the 2) OMF’s memory foam mattress (if we like its equivalent, the Tempur-pedic Rhapsody…and if we travel to the nearest OMF one Saturday and like it in person) idea.
But out of convenience and budgetary reasons, and this may change after we mattress shop on Wednesday, I’m leaning towards idea #1. In which case, knowing which name-brand “ultra firm” mattresses are recommended will be extremely helpful![/quote]
So now I’ve gone and given you an option #3 which may be the best value of all which is a “choose your own layer” in either memory foam/poly or latex with options available to customize both before and after purchase to reduce the risk.
Hopefully this LONG post has given you all the options you may ever need but if not keep the questions coming
Phoenix