This New Year’s Eve promises to be twice as memorable for those who book PrivateFly’s Celebrate New Year’s Eve Twice: The Ultimate 24-Hour Party package. Flying in a Gulfstream G650ER (the world’s fastest and farthest-flying private jet) across the International Date Line, travelers will be able to experience the stroke of midnight first in Sydney, Australia, and then in Los Angeles, Calif. Starting in the Land Down Under, guests can hang out at the Sydney Opera House, reserve a VIP table at the famous Marquee…