http://www.seatguru.com/airlines/Con..._777-200_B.php
Tell CO you have a baby, and want the bassinet seats 31 D,E,F. The bassinet attaches to the bulkhead wall in front of you after takeoff. They remove it right before landing, and the child is back in your lap.
When my sons were approaching 24 months, they were quite active, rambunctious. You are going to have your hands full. We did one trans-con with a 2-year old, then stopped flying them for several years, until the kids could sit still for 5 hours. Consider Benadryl to enhance their sleep, and have lots of fun surprises to play with while awake. Bring some of the child's favorite foods yourself!
It is cruel to the child (and to other passengers) to expect an energetic 2-3-4-5 year old to sit still in a hard seat for 15 hours.
B7