sidesleepy:
I’ll do my best to provide some general guidance. I’m limited in being too specific without visiting with you in person, but hopefully this information will prove to be useful.
The first thing to understand is that there is no one product that is best in general for pressure points. There is incredible variability among individuals as related to localized ischemia. Your level of sensitivity and tolerance of discomfort come into play. Your somatotype is important. For the hips, your level of flexibility of your outward rotators and IT band can have a great impact upon sleeping comfort. Even pillow thickness can impact low back/hips sensitivity.
Ideally, you want something to help maintain a relatively neutral alignment while assisting to distribute mass over a wider area. Too soft or minimal surface padding materials can cause one to “feel through” those layers to the deeper support unit, and this is why often mattresses that feel soft to the touch can end up sleeping “hard”. If the padding material “comfort cradle” is too deep, it can feel comfortable on top, but alignment can be negatively impacted, which will cause greater issues long term. The key is finding just enough padding material of higher quality and combine that with a support unit in a manner where they “blend together” and feel to work in unison as a complete unit (little “abrupt” transitions between layers).
A mattress using fabric encased springs with latex on top can be a very comfortable and supportive product. You don’t mention the specifics (thickness/density/ILD of materials on your current mattress), so I’ll make some general statements. A common configuration is 3" of latex atop an innerspring unit. If the latex is too soft, this can result in “feeling” more of the innerspring unit. If the waist/hip dimensional difference is great, it could be that a bit thicker comfort cradle would be needed. If a more substantial comfort cradle would be desired, latex in a higher ILD could be used, or increasing the thickness could help. Multiple layers, using latex on top and then something that feels a bit more dense, such as a higher quality memory foam or a good high density poly foam beneath the latex, could also help. For some people, they don’t like the feel of an innerspring unit for a support core and instead choose a high density poly foam support core or a latex support core. These can contour more “finely” to body contours.
And to note: high density poly foam doesn’t mean it feels “hard”. Density and poly foam softness are not mutually inclusive. Density would be more related to durability (higher mass per unit volume will be a more durable poly foam generally), and ILD / IFD would be the softness of the foam, which can be independent of the density. You can have a high density poly foam that is hard or soft. But with latex, density and hardness ARE related. Higher density latex is almost always a firmner feeling material.
As for memory foam, again you weren’t specific about layerings, so I’ll make some general statements. Memory foam isn’t a very supportive material. It’s imperative that for durability a higher density memory foam be used, and beneath the upper layer of memory foam, quality layer(s) of high density polyfoam be used as transition between the upper memory foam layer and the support core (poly foam or innerspring). Your comments of an old memory foam mattress “feeling flat” after a few weeks speak to the new foam losing some of its “false firmness” when new, and can represent that this product wasn’t substantial enough in quantity of material or quality of material in the deeper support layers (higher density foams). It could be that you’d like something contouring but more supportive on top, which again could be something like latex with memory foam underneath, and perhaps a little poly foam under that on top of a support core.
One of my favorite beds of yore used 2" of Talalay latex on top, and under that were 2 – 2" layers of 5# memory foam. Under that was a 1" piece of HD poly foam, and that was all on top of an HD poly foam core. What does that mean as it applies to you? Probably absolutely nothing. What I like and you like can be very different things. I just wanted to point out that the type, layering order, thickness, quality and total material amount can vary greatly, and sometimes it’s just the ordering to achieve the comfort you desire. There’s a reason mattress and foam engineers are highly skilled individuals. This stuff can take you down a rabbit hole to China.
If your pressure point relief needs are extreme, there are some very high quality true zoned latex mattress systems out there, with some extremely knowledgeable people that can help guide you through that process (the FloBeds vZone comes to mind). I don’t recommend attempting to design one of those beds on your own.
I know the information I provided is generalized and I really covered a ton of ground with some broad stokes, but without a more specific starting point this is the best I can do. Hopefully this is useful to you, and perhaps some other site members can chime in with a few other suggestions for you as well.
Good luck!