Just checked my log books and find I flew many sectors in 2001 Scandanavia-Canaries well in excess of 6hour block in a B738 with 27K engines.Typically 6 hours 10 minutes and always with a full load of 189 pax.I remember being amazed at the capability of these small aircraft at the time and always arrived very flush with fuel.Level of pax comfort in charter fit much better than the 75/76 in equivalent fit.Cockpit admittedly a bit cramped for this sort of trip but as we always got off for a few days layover unlike the cabin crew due to Scandic FTLs a rather civilised operation.The NG Boeings if decked out with powerful engines are very range capable which I believe is why my company got them as Airbus we,re very underpowered at the time and couldn,t get the payload/range necessary.