As an interim solution, I'd prefer hammocks, gently swaying to and fro like hanging cocoons, or at least bunkbeds stacked on either side of the aisle.
But long-term, we should pursue a design that consists of floor-to-overhead banks of beehive-hole tubes that we could crawl into and lie down for the entire flight. Inside each, we could adjust the lights, temperature, and volume of the PAs. Music and videos could be selected to an individual's taste. Pillows would be supplied, and each would be stocked with basic drink and foodstuffs. A well-padded interior would protect the individual from effects of turbulence. At one end of each tube would be a sliding door you could lock from the inside, and at the other a window with tint and polarization controls. First class passengers would occupy the top row, each of these being afforded a large skylight window in addition to their side one.
Each hive compartment would be soundproof, fireproof, (and since they are constructed individually) designed to break free, scatter, and bounce across the ground in the event of an off-aiport landing that results in an aircraft hull breakup. Inside their respective compartments, the passengers remains comfortable and unharmed as they cartwheel and scatter in all directions, away from the chaotic inferno of the crash site proper. Of course, each one would also float and thus serve as it's own flotation device (no more rummaging around for those cheapo, so-called "life" vests).
When boarding, anyone holding up the line because their carry-on won't fit through the opening of their hive-hole, would be shoved through a door at the rear of the airplane and ejected from the hive.