The 787 was designed to be a complementary type?
I know everyone thinks the 777 is a shiny new jet- but it's close to 20 years old...
Here's some 777 history from Boeing's website.
http://www.boeing.com/history/boeing/777.html
The Model 777, the first entirely new Boeing airplane in more than a decade, was the first jetliner to be 100 percent digitally designed using three-dimensional computer graphics. Throughout the design process, the airplane was "preassembled" on the computer, eliminating the need for a costly, full-scale mock-up.
The 777 program was launched in October 1990 with an order from United Airlines. In June 1995, United flew its first 777 in revenue service. The Boeing board of directors authorized production of the 777-300 on June 26, 1995, and the first 777-300 was delivered to Cathay Pacific Airways in June 1998.
The 777 is the widest, most spacious airplane in its class and includes improvements in airfoil technology, flight deck design, passenger comfort and interior flexibility. Its greater payload and range capability result in lower operating costs to airlines, and its standard equipment includes many features that are optional on other airliners.
The airplane is larger than all other twinjet or trijet airplanes but smaller than the 747. It brings the twin-engine economic advantage to medium- and long-range markets. The 777 currently is available in five models: 777-200, 777-200ER (extended range), 777-200LR (longer-range), 777-300 and the 777-300ER. The 777-200 can take 305 passengers 5,210 miles; the 777-300 can carry 368 passengers 5,955 miles. Launched in February 2000, the 777-200LR and 777-300ER can fly 8,818 or 7,175 miles, respectively. The 777-300ER rolled out Nov. 14, 2002