The best experiences would have to be the jumpseat landings:
F100 G-BYDN CDG-HEL Air France operated by Gill Airways
MD82 LN-ROU HEL-ARN Scandinavian Airlines
A320 C-FKPT ORD-YYZ Air Canada
DHC8 C-FHRC YQB-YUL Air Nova
Ansett Australia flight 888 from Hong Kong to Sydney was fantastic too, I was on the upper deck with 7 fellow passengers and two flight attendants.
Sadly, cockpit visits are likely impossible from now on and my beloved Ansett Australia is gone
Aviation won't be the same.