Gulfstream Aerospace introduced two all-new business jets in mid-October in a surprise ceremony at its production plant in Savannah, Ga. The Gulfstream G500 and G600 jets aim to provide speed and operating efficiency, plus wide-cabin comfort. Both airplanes can cruise as fast as an impressive Mach 0.90 (or about 680 mph), with a maximum range of a little more than 5,700 miles for the G500 and about 7,100 miles for the G600. 

The cabins in both aircraft will measure more than 7.5 feet wide and more than…