Hey Takk,
Welcome to The Mattress Underground 
! Thanks for stopping by and for your question.
[quote]I’m in the market for a new mattress, and a bit over my head.
My wife and I bought a Vera Wang Natural Charm mattress almost 10 years ago. We loved the original feel of that mattress. The trouble was, it only really lasted less than 5 years, and it was quite expensive. It also seems to fall into the generic “innerspring” category, but felt different than pretty much anything else we tried. I’m told that this line was one of the most “firm” mattresses that Serta ever offered, and we did like that an awful lot. Unfortunately, I can’t find much else for details about it at this point.[/quote]
Congrats on your new mattress shopping adventure ! Serta’s Vera Wang collection was quite popular 10 years ago and offered a variety of latex and hybrid models. A recent Phoenix postdiscusses some of the materials found in several of the models, as well as a YouTube look at one of their latex mattresses. Convoluted polyfoam seems to be used as a comfort material in this particular post, and several consumers report lower durability/ shorter useful life as you have too.
[quote]If I could find an identical mattress that was cheap and I didn’t mind replacing regularly, I’d buy it. Otherwise, I’d love to find a similar feel that will actually last.
My wife and I sleep in all different positions, so something general purpose is good. I will sometimes fall asleep on my stomach or back, but often wake up on my side. Same for her. Roughly 200 lbs each.
We don’t have much in terms of preference for brand or special features. Something somewhat firm ideally. Don’t care about isolation or anything like that.[/quote]
Thanks for including your personal stats and sleep preferences, Takk; you are on the right track going with a firmer mattress, considering both of your somewhat higher BMIs. As your Vera Wang Natural Charm used an innerspring support core, you may consider some variety of a hybrid mattress as an option. For those not familiar with the term, a hybrid mattress contains a coil system (often pocket coils) as a support unit, using foams as the comfort layer(s). Some find them to be a cooler sleeping mattress, as their designs promote natural air circulation. These fine TMU trusted members offer hybrid and innerspring mattresses, you may want to check their collections out.
[quote]The only other point of reference I have is our current mattress (borrowing our spare bedroom’s while we search, after we got rid of the other one), which is a Lucid 6 inch memory foam:
www.amazon.com/gp/product/B008S5AZRM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
We don’t hate the feel of that one overall, but we feel the bed frame through it pretty solid, not supportive enough over time. Maybe a thicker foam would have been OK? I don’t love the memory part, but meh.[/quote]
Thanks for including the Lucid product link for review, it’s helpful to save a click here and there when possible 
. This 6" all-foam mattress is straightforward: 2" memory foam over 4" HD foam, no densities given on Amazon’s site. If you can feel the bed frame through the mattress, a thicker version may be more suitable (this one is promoted as a kid’s model). Otherwise, its use of a spare bedroom mattress is probably adequate. What specifically do you not like about memory foam?
I searched online for more Natural Charm details, but as it isn’t currently available, there were only a few past mentions from review sites with no materials/ specs given. If any of TMU’s consumers can shed some light on its ingredients, please feel free to share . Good luck with your research Takk and hope this helps you get started.
Sensei