Whilst in essence these 'sightseeing' flights are a good idea, Singapore Airlines for example, have been doing them from Changi for a while I believe for a few hours roundtrip to nowhere, the Qantas flights are another level of magnitude altogether. How does ETOPS etc work when carrying passengers on such flights ? Whilst the reliability of the modern jets and their powerplants is exemplary, if some unanticipated Mx issue were to happen that needed a diversion, where the hell would/could you land ? Possibly an emergency landing at McMurdo, but that might be a one-way affair. I wouldn't feel comfortable doing such a flight, and certainly not paying for the pleasure. Great idea, bad destination imho. As has been mentioned the ANZ crash made for sobering reading. Btw, did the crashed ANZ DC-10 ever visit LHR back in the day ?
Speaking of long flights, Lufthansa is preparing to fly a plane load of scientists from Hamburg to Port Stanley (FI) on Feb 1st to meet up with their research vessel going to the Antarctic. Apparently the flight will take 15-16hrs nonstop, not sure if they'll use an A350 or A340.