UA 747-100 or 747-200 from LAX to HNL back in 1997. Really wanted to visit the upstairs as a kid. Finally got the chance to do that on a 744 in 2017
Miami Air 727-200 in my childhood. Forget the exact year. We sat up front and I still remember it being loud.
ATA L-1011-500 in 2000 from NGU-BWI-KEF and back. Sat next to the galley and was fascinated by the elevators.
Air Transport International DC8 Combi in 2011 from BWI to TER. Had passenger seats only in the very back along with a high definition overhead IFE system. The presence of the fancy IFE system was overshadowed by the fact that they only showed the movie Unstoppable in both directions.