This barely counts as 'leisure', but it was the furthest I've ever flown.
LHR-SFO-SYD-MEL, 3 days personal time for a funeral, then MEL-SYD-SFO, work for a week, then SFO-LHR.
LHR-SFO-SYD-MEL was in Y.
Totalling up the transit time, I spent in aircraft 41 hours (26 to get there, 14 back to SFO) to spend 72 hours in Melbourne.