Boasting the longest range of any business jet in service, the Gulfstream G650ER (gulfstream.com) can fly more than 8,600 miles nonstop at a cruising speed of 562 mph (when transporting eight passengers and four crew members). The $66.5 million jet is an enhanced version of the G650. It can carry 4,000 additional pounds of fuel compared to the G650, which enables it to travel nearly 600 miles farther. (For $2 million, Gulfstream will upgrade an existing G650 to G650ER specifications.) Under the right cond…