My best suggestion would be some sort of guilty pleasure that you would enjoy that is available only on the plane. Doesn't have to be exotic. Just something you can't do anywhere else (oir at least easily elsewhere). So depending on the flight length, maybe you like to listen to show tunes or watch mockumentaries or disconnect from the world.... something you won't let yourself enjoy on the ground or at home.

As for convenience, I am trying to pack a travel kit that has some creature comforts I will need in the air that I can quickly remove from my backpack without moving around. So it will have a few snack things, cables and a fan/hand warmer (if I happen to get the exit row). When I get to my seat, I pull out three things... the kit, my tablet and my headphones. I shove my backup in the bin and I'm all set to zone out.