Hi dinobyte217.
Welcome to our Mattress Forum. 
The first place to start with any mattress research is always post #1 here no matter what your weight or sleeping style (the basic principles are the same). It has all the basic information, steps, and guidelines you will need to make the most suitable choices.
There are also a number of forum posts and threads about mattresses and higher weights and a forum title search on heavy (you can just click this) will bring up many of them. Some examples include post #2 here and post #2 here and this thread.
By your post, it would appear you’ve already done some research and landed on latex as you best option. I would agree with that, but while your partner and you may share similar weights, it’s very possible you still need very different things from your mattress, especially if you have different support needs, pressure points, or sleeping positions. You may also wish to consider a split configuration.
I would suggest checking these options out…
Arizona Premium
Sleep EZ
FloBeds
Latex Mattress Factory
Nest Bedding
As you can see in mattress firmness/comfort levels in post #2 here … I can only speak to the quality or value of a mattress or help with “how” to choose because there are too many unknowns and variables for anyone to make specific choices for others based only on very limited information.
With your higher weight though the materials and components in a mattress will soften and break down much faster than the norm for other people so it would be particularly important to choose the highest quality and most durable versions of any material you prefer to use in a mattress. Firmer choices will also be more durable (and feel softer to you than they would for people that are lower in weight because you will sink into them more). You can read more about some of the factors involved in durability in post #4 here.
No matter what your weight or body type … the combination of PPP (Posture and alignment, Pressure relief, and Personal preferences) that is most suitable for you is just as important as it would be for anyone else. You will just need firmer and more durable materials and components in the support and comfort layers of a mattress to achieve it than someone else who is lighter. Who you choose to deal with and their knowledge, experience, and integrity can also be one of the most important parts of making the most suitable mattress choice.
NikkiTMU