Hi confused1,
I keep starting a reply to your post only to find that by the time I complete the reply you have deleted the original post. Hopefully the third time is lucky and your post is still there by the time I finish my reply 
Post #2 here has more about the different ways to choose the most suitable mattress or layering combination (either locally or online) that is the best “match” for you in terms of “comfort”, firmness, and PPP (Posture and alignment, Pressure relief, and Personal preferences) that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for.
If you are working with a local store then a knowledgeable and experienced retailer will help you narrow down your choices to a much smaller subset of combinations (perhaps half a dozen or less) based on the “averages” of other people that are similar to you in terms of their body type, sleeping style, or preferences so you can choose which of them is the best “match” for you based on careful testing (hopefully using the testing guidelines in step 3 of the tutorial). Many of the “possible” combinations wouldn’t be useful or practical anyway (such as having the firmest layers on the top and the softest layers on the bottom).
When you can’t test a mattress in person then the most reliable source of guidance is always a more detailed phone conversation with a knowledgeable and experienced retailer or manufacturer that has your best interests at heart and who can help “talk you through” the specifics of their mattresses and the properties and “feel” of the materials they are using (fast or slow response, resilience, firmness etc) and the options they have available that may be the best “match” for you based on the information you provide them, any local testing you have done or mattresses you have slept on and liked or other mattresses you are considering that they are familiar with, and the “averages” of other customers that are similar to you. They will know more about “matching” their specific mattress designs and firmness levels to different body types, sleeping positions, and preferences (or to other mattresses that they are familiar with such as different Savvy Rest combinations) than anyone else.
Phoenix