When BA introduced the 747-400 in to its LHR-SIN-Syd/Mel routes, they had a lot of teething problems. I used this route quite a lot, and had
1. 24 hour delay at LHR
2. Flight diverted to Athens. Some technical fault.
3. Transferred to an SQ flight from Sin to MCR
4. Flight diverted to AMS. (Crew ran out of time)

Of these, the time in Athens was the best. BA had 4 very senior guys from their then biggest customer on board, 3 in F. The Station Manager at Athens gave us some Greek money, and 2 of us took a taxi to a Bar by the sea near Athens somewhere. We drank rather a lot of Metaxa. And a modest amount of coffee.