Delta now flies mostly B777's via transpacific and transatlantic. The seating configuration, on Delta's aircraft, are 3-4-3. However there are a few two seat configurations on this aircraft. When you go into Delta's website and start a booking the seating availability will be shown prior to paying. I have not found one flight where the twin seats were available. No matter how far out I attempt to book, even 6 months. I cannot believe that all the twin seats on all of these flights over 6 months are not available. They must be routinely blocked by Delta possibly to accommodate their Medallion members as first priority. I have not found this to be the case will all airlines. Some of the Asian airlines have the twin seating indicating availability before booking.