[jryle70]

Airlines use longer range aircrafts for longer flights. That should be obvious, shouldn't it?

[Retric]

Efficiency is one way to increase range. Wingtip devices can reduce drag by inhibiting vortex formation, however they increase weight so there is a minimum flight distance before they are a net gain. https://en.wikipedia.org/wiki/Wingtip_device

There is a tradeoff of needing carry more fuel over a portion of the flight, but the aircraft also spends a higher percentage of it's fuel on flying vs taxiing etc.