Hi BedNeeder,
The previous post I linked has more information about the best ways to choose a mattress that would be the most suitable choice for her in terms of PPP.
There is also more about the most important parts of the “value” of a mattress purchase in post #13 here which which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability (how well she will sleep), durability (how long she will sleep well), and the overall value of a mattress compared to your other finalists (based on all the parts of your personal value equation that are most important to you).
Unfortunately it’s not possible for me to make specific suggestions or recommendations for someone else or about which combination of materials or firmness levels will work best for her because the first “rule” of mattress shopping is to always remember that she is the only one that can feel what she feels on a mattress and there are too many unknowns, variables, and personal preferences involved that are unique to each person to use a formula or for anyone to be able to predict or make a specific suggestion or recommendation about which mattress or combination of materials and components would be the best “match” for her in terms of “comfort” or PPP (Posture and alignment, Pressure relief, and Personal preferences) or how a mattress will “feel” for her based on specs (either hers or a mattress) or “theory at a distance” that can possibly be more accurate than her own careful testing (hopefully using the testing guidelines in step 4 of the tutorial) or her own personal sleeping experience (see mattress firmness/comfort levels in post #2 here).
When you can’t test a mattress in person then the most reliable source of guidance is always a more detailed conversation with a knowledgeable and experienced retailer or manufacturer that has your best interests at heart (such as Dreamfoam) who can help “talk you through” the specifics of their mattresses and the options they have available that may be the best “match” for here based on the information you provide them, any local testing she has done or mattresses she has slept well on and liked that they are familiar with, any special considerations she may have, and the “averages” of other customers that are similar to her. They will know more about “matching” their specific mattress designs or firmness options to different body types, sleeping positions, and preferences or even to other mattresses that they are familiar with than anyone else.
Phoenix