"Boeing plans three versions of the 787 -- a short-range 787-7, the long-range 787-8 and 787-9, which will be bigger.
Boeing does not want to make the 787-9 too big or it would be competing against its 300-seat 777-200." I do not know"777-200"thank you
777-200, 305 to 440 seats, 5,302 cu ft of cargo space (up to six pallets, 14 LD-3 containers, plus 600 cu ft of bulk cargo), typical cruise speed mach 0.84, max range 9,649km.
http://www.boeing.com/commercial/777family/777technical.html
The current rumors coming out of Boeing is that the company is looking at de-emphasizing the 777-200A/ER models in favor of more 777-200LR and 777-300ER sales. This will allow Boeing to stretch the 787 design even further than the the 787-9 design; the result--using an uprated version of the GENx or Trent 1000 engine--could be a plane that seats almost the same as the 777-200ER but will burn less fuel per passenger and probably have a range as far as 8,000 nautical miles. Of course, the big advantage of the 787 design--namely the improved cabin pressurization system that allows for the equivalent of 6,000 feet altitude at all times--will be part of this extra-stretched 787.