I was just thinking. I think the longest time I've spent getting from one place to another has to be when I went to DIEGO GARCIA in October of 1987. Here is how that trip went.
JAX-ATL-SFO-HKG-SINGAPORE-DIEGO GARCIA.
I had three nights in Singapore before I completed my last leg since SINGAPORE to DIEGO GARCIA had only one MAC flight per week going to that island in the middle of the Indian Ocean. But nonetheless, just getting to Singapore was a nightmare. MISERABLE. First off, it was a military contract so right there, that means NO FIRST CLASS. Add up the hours on each leg plus layovers and by the time I hit Singapore and layed in my hotel room , I was awake for well over 30 hours. The longest leg being at least 14 hours. So I calculate just flight time alone, Jax to Atlanta one hour, Atlanta to SFO at least six hours, SFO to HKG at least 14 hours, and to singapore from HKG another 5 hours. So I'm at 26 hours flying time ONLY not including layovers, so if you add the final leg three days later, its up to 31 hours of flying alone. Some other notable long trips I have made, and at times three or four or more of the same legs...you calculate those flight times.

IAH-NEWARK-BEIJING

SPN-GUM-NRT-ORD-BOS

Jax-Det-Nagoya-Gum-Saipan

Jax-Det-Seattle-Nrt-Gum-Saipan

MNL-Gum-HNL-IAH

IAH-SAO PAULO-BUENOS AIRES

SAO PAULO-NEWARK-IAH

ANTWERP-AMSTERDAM-ATL-JAX

Jax-ATL-JFK-LONDON-BAHRAIN-DAHARAN

IAH-SEATTLE-ANC

DIEGO GARCIA-SINGAPORE-NRT-SEATTLE-SALT LAKE CITY-CHICAGO

GUM-NRT-SFO-CHIC-JAX