The777Man From United States of America, joined Jul 1999, 6310 posts, RR: 56 Reply 7, posted (10 years 7 months 1 day 22 hours ago) and read 1896 times:
They are newer and therefore need less maintenence but also more versitile; can fly short flights as well as Transcontinental flights. The 737s don't have the range for Transcon. flights. This is just my guess; nothing official from United Airlines.
Need a Boeing 777 Firing Order....Further to fly...T5, CI, LX and LH 777s