Hello biggerbedpls!
Welcome to our Mattress Forum! 
It’s always gratifying our TMU moderators when our visitors are doing some preliminary research so it is nice to see that you are already quite deep into it.
I am not sure what the weight differential between you and your partner is, but you may be surprised that some types of layering may work well for both of you, even with you being shorter and having wider hips and shoulders (which need a bit more cushioning for your side sleeping) You have a good starting point as both of you seem to be mainly back sleepers. You may even find that due to your body conformation you may benefit more from a zoned construction. I don’t know the width of the center third zoning in the combi-zone unit but I suspect that you are still tall enough and that your hips and shoulders would comfortably rest on the top/bottom zoning if you position yourself with your waistline in the center zone. Horizontal zoning can be successfully used in a less thick bed design to introduce some adaptability because in the case of a thicker mattress that is easier achievable with slightly thicker layers that can “act” softer and you can use firmer layers on top that are more adaptable to a greater range of weights and sleeping positions. See post #14 about layer or mattress thickness
Without knowing your BMIs it’s hard to make specific commentary. If you’re both within a similar BMI range, it’s very possible that a zoned mattress could be a perfectly acceptable option. If one of you is very heavy, and the other very light, one of you may struggle to find comfort based on the support factors involved and may want to consider a split mattress instead. You can read more here about side by side layering in post #2. One really high-quality option sold by one of our valued trusted members on the site is the Alexander Nest Bedding Split King Hybrid (within your budget!). They are extremely knowledgeable and transparent and would be able to answer any questions you have regarding your sleep styles, height differences, etc.
Much of mattress buying ultimately comes down to PPP (Preference, Pressure relief, Posture, and alignment) – so I am glad that you are looking at good return policy options. I’d make sure to call each of your finalists to get some guidance and help to “talk you through” the specifics of their mattresses as it relates to partner differences and what zoning is likely to do for you…
All beds you mentioned could work out for you. but some use slightly different Combi-zone units in their designs and you would need to talk with the manufacturers to see how these differences translate withing their designs.
For example, Arizona and Avocado use QE Combi-Zone® 8" Leggett & Platt Quantum Edge Combi-Zone For the Queen: 1,130 support coils
— Perimeter, Top + Bottom: 144 coils (16 gauge, 10 turn fabric encased coils)
— Perimeter, Sides: 200 coils (16 gauge, 10 turn fabric encased coils) ~ NARROW diameter
— Head + Foot: 462 coils (14 gauge, 5 turn fabric encased coils)
— Center: 324 coils (17 gauge, 10 turn fabric encased coils)
My Green Mattress seems to be using a slightly different Combi-Zone with 1,074 springs, for enhanced lumbar and edge support.
• - 8" tall coils (8 turns)
• - 13.5 gauge perimeter for a firmer seating edge,
• - 15.5 gauge coils Head + Foot sleep surface
• - 14.5 gauge coils throughout the center third of the mattress for improved lumbar support.
These fabric-encased innerspring (made from recycled steel) are arranged in 3 distinct zones with a reinforced perimeter to float independently and reduce motion transfer.
There are also several ways to accommodate two people who have very different needs and preferences on the same mattress discussed in the first part of post #2,(sleeping hot is discussed in part 2 of the same post) but side to side split layering can be one of the most effective if your testing indicates that most of the “non-split” layering you’d test doesn’t work equally well for both of you
Provided that you talk through with the manufacturer/retailer of your contenders and give a “fair try” to a zoned system, here are some not zoned options to look at.
Alexander Nest Bedding hybrid mattress is not zoned.
The GhostBed Flex has Spirited Edge™ support coil unit that is not zoned (just edge support).
The Luma Mattress is a latex + coil hybrid that doesn’t appear to be zoned, either.
I’d recommend combing through the hybrid mattresses offered by our many Trusted Members because I’m certain there are more. Many offer discounts to forum subscribers as well, so definitely keep your eye out for those!
Which of these would work best would depend on the needs and preferences of each couple. Careful testing with both of you on the mattress can tell you whether any of these options would be a good match for both of you but if you are considering an online choice where you can’t test the mattress in person this is where the help and guidance of a knowledgeable and experienced manufacturer or salesperson who knows every detail of the mattresses they make and sell, how they interact with different people and couples, and that has your best interests in mind can be invaluable.
I look forward to any additional questions you may have, or just hearing any updates you may have!
Phoenix