Hi billy1956,
Welcome to The Mattress Underground 
[quote] We found a manufacturer in NC. that offers a split head mattress. They will make it to our preference and ship in a box. We have Twin Size Rize adjustable bases that will work separate of each other. This is the make up that we are considering. What are your thoughts?
(13")Split head Queen mattress
2" Quilted Organic Cotton fabric( has gel infused visco)
2" Gel Infused Visco
3" Latex C4 or C3?
6" HD Poly Foam.[/quote]
A split Queen is a good solution for partners with different sleeping styles, sleeping positions, and firmness/comfort needs. The adjustable bed in combination with a split mattress will also be able to accommodate different elevation needs for both sleepers. So, you are going in the right direction. First off I’d pay attention to the quality of the materials in this mattress (foam densities, especially the top 4 inches of memory foam which tells you about its durability and for how long you’ll sleep well on it before the foams start to break down). I would always make sure that you find the mattress specifications you need to know so you can compare the quality of the materials and components to the mattress durability guidelines here Have you tested a similar mattress? (including the type of materials used}
You are not mentioning your BMI, height, weight, or history with your current mattress in your personal stats to be able to give you some more pointers. 13" profile is a fairly thick mattress. Do you need that much height? When you say ‘twin size rize adjustable base’ - Rize seems to make both twin and queen size – but I’d make sure that the mattress complies with the Rize warranty & vice versa as a queen mattress will not fit a twin mattress base.)
If you are questioning which mattress type or firmness level would be better for you and your wife this would be impossible to know for sure as you are the only ones that feel what you feel on any specific mattress but … there is some fairly extensive general information in the mattresses section of the site (particularly in the sections about sleeping style, preferences, and statistics along with putting the layers together and the page on tips and tricks here) that can give you some general concepts, guidelines, and insights about the effects of different body types, sleeping styles, and mattress designs for different people but this is only generic and not specific to any particular person and may be more complex than you really need to know.
The mattress shopping tutorial here has the basic information, steps, and guidelines including suggestions about how to test a mattress for what I call PPP (Posture and alignment, Pressure relief, and Personal preferences) that can simplify your search and help you make the best possible choices. Perhaps most importantly it can also help you avoid the worst ones (like the major manufacturers or any manufacturer or brand that doesn’t disclose the quality of the materials in their mattresses and most mass-market stores that have little knowledge about the mattresses they sell). Did the manufacturer in NC provide the densities of the top 4 inches of foams used in the bed they can build for you?
If personal testing on similar mattresses locally isn’t possible (either because there are no reasonably similar mattresses that you can find locally or because you have difficulty finding out more detailed specs of mattresses you are testing) … then the next best way is more detailed discussions with an online manufacturer or retailer themselves. They are much more familiar with their own mattress designs and materials than anyone else (including me) and they can use the information you provide them about your body type and sleeping positions, your preferences, your history on different mattresses, and the results of your local testing to make suggestions based on the “averages” of other customers that may be similar to you. The more accurate and detailed the information you provide them the better you will help them to help you make the best possible choices out of the options they have available. Of course the options you have available with each retailer or manufacturer (or with a particular mattress) and your ability to exchange layers or the mattress itself or use other forms of fine-tuning after your purchase or the return policy may also be an important part of your personal value equation or to offset the risk that can go with any online purchase.
Post #2 here also has more about the different ways to buy a suitable mattress (either locally or online) that is the best “match” for your body type, sleeping positions, and preferences that can help you assess and minimize the risks involved in each of them.
So I’m always happy to help the forum members here with “how” to choose, to act as a "fact check, or to help them find better manufacturers or retailers that have better quality and value but “what” to choose in terms of either a mattress or the balance between comfort/pressure relief and support/alignment that may be suitable for a specific person is always up to the only person who can feel what you feel on a mattress and best left to personal testing and your own experiences or more detailed discussions with the more knowledgeable people at the retailers or manufacturers that sell a mattress you are considering.
Phoenix
Note added later.: I have moved your second post to the same thread to add it to the info and your stats