JNB-JFK and vice versa probably more than 20 times. (Both nonstop and with stops in SAL and DKR). I was on the inaugural JNB-JFK flight without a refueling stop, Port Authority Fire Dept met us on the tarmac with a congratulatory hosing.
Worst flight was JNB-AUH-JFK (2 hour layover was enough for a quick shower in the lounge, but that did little to alleviate the torture of that 14 hour second leg.) The outbound - JFK-AUH-JNB had an overnight layover and was a breeze in comparison. ($300 "glitch" flight)
JFK-SFO-SYD-MEL & MEL-PER-SFO-JFK (if memory serves)
JNB-Europe & NYC-Europe and vice versa many many times, honorable mention for awful suffering to Air India's CDG-JFK.