Hi soldat88,
It’s unfortunate that you didn’t post on the forum before you made your purchase because I would have replied with a post that was the same as post #2 here and strongly cautioned you about purchasing any major brand mattress including a Simmons.
I would have also cautioned you about considering any hotel mattress such as the Westin (or trying to “match” it) which are usually just a very basic (and often lower quality) version of similar mattresses that are made for consumers by the same manufacturer (in the case of the Westin made by Simmons). There is more about hotel mattresses in post #3 here. In many cases if people sleep well on a hotel mattress it can say more about their own mattress needing replacement than it does about the hotel mattress itself.
I would also have cautioned you that there are too many unknowns, variables, and individual preferences and circumstances involved to be able to predict whether adding a topper or a mattress pad to a mattress you purchase will make it “feel” like another mattress that has a completely different design outside of comparisons that are based on your own careful testing and experience on the actual mattress and mattress pad combination because different people can have very different opinions about how a mattress in combination with a mattress pad or topper will compare to another mattress if they have a different body type, a different sleeping style, are used to sleeping on a different mattress, or have different sensitivities and preferences than you do.
There is more information in post #9 here about the different ways that one mattress can “match” or “approximate” another one. Every layer and component in a mattress (including the cover and any quilting materials) will affect the feel and performance of every other layer and component and the mattress “as a whole” so unless you are able to find another mattress (and mattress pad or topper) that uses exactly the same type of materials, components, cover, layer thicknesses, layer firmnesses, and overall design (which would be very unlikely) then there really isn’t a way to match one mattress to another one in terms of “comfort”, firmness, and PPP (Posture and alignment, Pressure relief, and your Personal preferences) based on the specifications of the mattresses (even assuming that you can find out all the specifications you would need for both mattresses you are comparing in the first place).
Mattress manufacturers generally try to differentiate their mattress from the mattresses made by other manufacturers and don’t normally try to “match” another mattress that is made by a different manufacturer so unless a manufacturer specifically says in their description of a mattress that one of their mattresses in the same general category is specifically designed to “match” or “approximate” another one in terms of firmness or “feel” and PPP and/or they are very familiar with both mattresses and can provide reliable guidance about how they compare based on the “averages” of a larger group of people that have compared them then once again the only reliable way to know for certain how any mattress/mattress pad combination would compare for you to another mattress in terms of how they “feel” or in terms of firmness or PPP (regardless of how they would compare for someone else) would be based on your own careful testing or actual sleeping experience on both of them.
If a mattress is a good match for you in terms of PPP then all you need is a mattress protector that can be removed and washed on a regular basis to keep your sleeping surface in a clean and hygienic condition and to protect your mattress from the body fluids and oils and skin flakes that we release each night, help to reduce dust mites, and to protect against any accidents that can stain your mattress and void a warranty. The “ideal” protector would be relatively thin and stretchy so that it would have the least possible effect on the feel and performance of the mattress. There is more about the pros and cons of different types of mattress protectors and some examples of each of them in post #89 here.
A mattress pad is thicker than a mattress protector and is normally used to fine tune the “feel” of a mattress and to add some additional surface softness. If your mattress doesn’t need any fine tuning then you wouldn’t need a mattress pad because they can interfere with the feel and response of the softer layers on top of the mattress and can sometimes reduce their ability to contour to the shape of your body. Some mattress pads are either water resistant or have a waterproof “semi breathable” membrane and can serve a dual function and can be used to protect a mattress as well and if you use one of these then you wouldn’t need a separate mattress protector.
I don’t recommend any specific mattress protector, mattress pad, or topper because this would be a personal preference and each person has different criteria that are most important to them but there is more about the differences between mattress protectors, mattress pads, and mattress toppers in post #10 here.
I or some of the more knowledgeable members of the site can certainly help you to narrow down your options, help you focus on better quality/value choices that are available to you either locally or online, help you identify any lower quality materials or weak links in a mattress that you may be considering, act as a fact check, answer many of the specific questions you may have along the way that don’t involve what you will “feel” on a mattress, and help with “how” to choose but only you can decide which specific mattress, manufacturer, or combination of materials or components is “best for you” based on all the parts of your personal value equation that are most important to you.
Unfortunately most of the questions you are asking would have been better asked before a purchase but once you have already made your purchase … unless you are able to return your mattress for a refund and start over again … any help I can provide is very limited.
Phoenix