Food on most flights, and smoking sections as others have noted.
Bigger planes and fewer passengers. I use to fly TWA frequently, taking an L1011 from STL to BOS. I don't remember it ever being full. Also was on TWA STL to BWI one time, 727, with 13 passengers.
More hubs offering more places to connect, like BNA, MEM, MCI, PHX, LAS just to name a few that I remember.
Hotel stays for overnight misconnects.
Flying wasn't glamorous in the 80's, but considerably less stressful than it is today. On the other hand, it seems like every year there were major plane crashes, so that was more of a worry.