DC-3 from Omaha to Fargo, ND - probably 1966 or there abouts. What I mainly remember is that it was a 'milk run' and we stopped numerous times, with passengers getting on and off. Pretty sure that was my first ever time on an airplane. No idea who the operator was.
First jetliner was a DC-8 60 series charter in 1972 - Denver to Switzerland (probably Geneva), with a couple stops (IIRC, Kansas City and Bangor, Maine). Overseas National Airlines - full of 250 teenagers and a few chaperones.