If I were designing an "ideal" single-aisle cabin for domestic US service, it would have the following:

F: sleeper (not flat bed) seats, 2x2, pitch 50+". 1 row on a 738/A320 or smaller model aircraft; 2 rows on a 757/A321 model.

C: recliner seats, 2x2, pitch 42-44" (enough to get out w/o the other person standing) w footrests. 3 rows on the small planes, 5 rows on large planes.

Y: 32" pitch.

Domestic C is, IMHO, a hugely untapped market, if priced correctly. For flights of 3+ hours, the combination of space to work and basic in-flight amenities (i.e., food or the ability to sleep) offers tremendous value add for biz travel, and if priced right should sell pretty full. My domestic F would primarily be targetted at international connecting pax.

If I were setting a pricing model, there would be 3 tickets in Y and 2 in premium cabins: unchangeable (Y only); changeable (but not refundable); and refundable. Unchangeable Y would be exactly what it seems - just like when you buy movie tickets online, once you click "buy", it's yours whether you show up or not; no refunds, no exchanges, no sob stories, period finished end. Changeable would allow you to swap the ticket to the same route, but a different flight/date, subject to availability of changeable (or, in Y, unchangeable) itinerary; I would also allow full $ credit for a changeable ticket being used against a changeable ticket on the same route in a higher priced cabin. Refundable is exactly what it says. (And, in my FF plan, those 3 tickets would get miles/status at 50%-100%-150%.) In setting prices, changeable would be 2x unchangeable Y; refundable Y would be 3x unchangeable Y; changeable C would be 2.5x unchangeable Y; refundable C would be 4x unchangeable Y; F pricing would be deliberately outrageous on a standalone basis (sort of like JFK-LAX is now!).

Every flight would offer meals in F&C; the 2 cabins would be served together from a galley at R1 (yes, even though that means walking thru F...) on smaller a/c, or from a galley at R2 on the 757/A321 size.