The longest flight I did was when I returned from a visit to New Zealand in 2004:
Invercargill -> Christchurch -> Auckland -> Los Angeles -> London LHR -> Edinburgh
The journey took around 36 hours and was largely uneventful. What I did learn was to check your baggage weight allowances; I ended up wearing quite a few of my clothes on the Invercargill to Christchurch leg :)
The Invercargill flight wasn't on my original itinerary as I thought I'd be driving up to Christchurch to catch first leg. So when I rolled up at the Invercargill check in I got a surprise:)
Invercargill -> Christchurch -> Auckland -> Los Angeles -> London LHR -> Edinburgh
The journey took around 36 hours and was largely uneventful. What I did learn was to check your baggage weight allowances; I ended up wearing quite a few of my clothes on the Invercargill to Christchurch leg :)