A no-flip mattress is a legend, a veritable El Dorado of the mattress world. That is to say, not a reality. Flipping a mattress is a pain to the consumer--they're heavy, they're ungainly. Making a mattress that is the same on both sides, i.e. twice as much material, is a pain to the manufacturer--they are more difficult to make and can't be as fluffy. So, how does one take this problem on and attempt to solve it? there are three philosophies.
The classic mattress: same on this side as it is the other. Flip it once a month and it will treat you right. Yes, it's difficult to do--they are quite awkward, and definitely hefty--but the alternative is night after night of getting into bed and rolling, beached, into the center of the mattress. An unpleasant prospect.
These mattresses are generally on the firm side of things, since a pillowtop that is too fluffy will won't allow the mattress to sit in the frame evenly (because with a two-sided mattress the pillowtop is also a pillowbottom). Their pillowtops are normally thin, if present at all.
This is a mattress built in one direction:up. That about sums up this rather simple and short sighted mattress-building technique. Make the mattress as tall as possible, and go in only one direction. They are generally quite thick, and consist of a base with various amounts of soft layers, comfort fills, gels, foams, and pillowtops, etc., and so on, sewn into the top. They aren't so much a no-flip mattress as much as a can't-flip mattress. What inevitably winds up happening is the area where you sleep every night quite quickly get's a depression--what's called in the biz a body impression.
Body impressions are an unhappy side effect of using soft materials which, due to being soft, break down much faster than the bulk of the mattress. The way to mitigate this problem is to flip and rotate the mattress, evening out where you sleep and letting everything wear more easily. But when you can't flip your mattress, you can't avoid these body impressions and will soon find that getting out of bed is harder, not because you're so comfortable, but because you're stuck in a once-fluffy crevasse.
The third and final philosophy--the one we ascribe to--doesn't fight the need to flip a mattress, but rather recognizes that the different materials used to build a mattress require different care, and therefore would do better on their own. So, instead of small pillowtops on each side, or massive ones on one side (that don't last long) we just made our mattress in two pieces. The lower support layer is thick and resilient, doing the heavy lifting of keeping your spine straight and your hips and shoulders properly elevated. This material doesn't need to be flipped that often - once every few months with springs and about twice a year with latex.
The second layer is the comfort layer, and it is separate from the support. This layer has varying thicknesses to suit different firmness preferences and works to fill the gaps of the body, contouring to all the various curves. This layer needs to be flipped more often--whenever you change the sheets. However, it is light and easy to handle and won't ruin your day anymore than changing the sheets already has. Which we hope isn't much.