Thanks for your comments and welcome
The easiest one first. We also watch movies in bed and so did a lot of research into adjustable bases. We ended up buying a Reverie Deluxe from here http://www.adjustablebeds.org/reverie_deluxe_adjustable_bed_with_wireless_control_and_massage-9981.aspx which have among the best prices that I know of for adjustable bases (unless someone who sells you a mattresses is willing to give you a comparable discount if you buy the whole set from them). Ours was a queen though which is considerably less than a king which can only be purchased in a “split” version so you would be buying two twinXL adjustable bases to make up a king. The advantage to this is that each side can adjust separately if you also have separate mattresses on each side. There are lower cost versions as well without the massage feature.
In terms of a mattress layering … a good place to start as far as the thickness of a comfort layer for a side sleeper is 3", Back sleepers would be about 2" and stomach sleepers need the thinnest comfort layer of all or around 1". The softness/firmness of a comfort layer is usually around 19 - 24 ILD with heavier bodies being firmer and lighter bodies being softer. Lighter bodies can also use thinner comfort layers. The middle and lower layers or support core should be firmer since this is the part that keeps your spine in alignment and prevents your heavier parts from sinking in too far.
There are several directions you could go. One is to find a happy medium in a comfort layer which would probably be in the range of 2". The thinnest/firmest that would provide both you and your wife with acceptable pressure relief (you on your side and her on her back) would be the best to also accommodate your stomach sleeping which should have the thinnest/firmest comfort layer possible. I would pay particular attention if you go this direction that your stomach sleeping position is not “swayback” (your hips sinking in too far) and putting your spine out of alignment.
The second direction that may work even better would be to buy a mattress with a different layering on each side all enclosed with a single zip cover or ticking. They are quite popular these days because it is not uncommon for a couple to have different needs in their mattress construction. Most of the DIY manufacturers offer this including those that are DIY manufacturing members here and they are usually the same cost as mattresses that have the same construction on both sides. They have a zip cover and you place the layers in the cover when it arrives and zip it up.
The best way to accomplish this is to do some field testing locally to determine the best construction and layering for each of you and then “duplicate” it through one of our online DIY manufacturers who ship across the country. If you get it a little “wrong” … then its simply a matter of exchanging a single layer of your mattress for a different firmness which is quite inexpensive rather than the much greater expense of sending back a whole mattress.
The third way of course would be to buy singleXL for each of you that together would be king size but this is generally the most expensive (although you can then adjust each side of an adjustable base separately) and doesn’t go together as snugly as a side to side split construction mattress (where you don’t feel the “split”).
Of course field testing mattresses to find the construction that works best for you is the most accurate way to find out what type of layering works best for each of you so these are general recommedations.
There are more manufacturers in east and west PA but these would be well worth checking out if they are close enough to you …
http://www.ashleyfurniturehomestore.com/storelocator/storelist.aspx?countrycode=USA&country=United%20States&statecode=PA&state=Pennsylvania (they have mattresses with latex comfort layers over a polyfoam core which can be a good lower cost compromise)
Furniture Row® Store Locations - Store Hours & Addresses (they carry latex mattresses with only 1" of polyfoam which I consider to be the maximum “acceptable” amount of polyfoam in a comfort layer however they are in York so I don’t know if this is close enough to you)
Let me know if I can help with any other questions or ideas.