One request is if you move forward with this is to be realistic to timeline on some of these things for the ultra long games. This way you have to actually make mods along the way to stay competitive on long haul routes.
A couple things to consider
Not sure if you ever flew a DC-8, but the movie was shown on pull down screens from the ceiling that you had to duck under. DC-10s got the screens on the galley wall / center divider but certainly no in seat entertainment systems or lie flat business seats.
On the other hand you could let us kit out our DC-10s and 747s with lounges and a piano...could actually be done on 707s and DC-8s too. Trade off would be seats for RI or something. Google seat maps and or just you tube DC-10 commercials for the 1970s.
For the pre 1965 era, you could also offer sleeping bunks for constellations, DC-7s etc.
In terms of the lie flat seats, I want to say British airways was first in around 2005? So it would seem like something like the lie flat premium seats (I like the design) should be introduced like a new plane type. Take a 777...if you order them in 1995 you can put in premium F and C but no bed seats. Then you have to decide if you upgrade to lie flats in 2005 when they get introduced (same concept as upgrading engines in terms of a cost and downtime). To make it interesting, Premium RI on routes over 3000nm starts to decline from 2005 onwards once someone installs them. if you don't have lie flats in your f and c cabin but a route competitor adds them, then presumably you aren't as competitive as your competitor and business travelers start to fill your competitors cabin.
Long story short, hope you make these features era specific and they have some material impact on the operation, rather than some nice looking toys...especially if you go through effort with all the programming.