BKK is pretty low season this time of the year, so ID90 might be an option. Suppose there's not much in the way of time difference if you go East or West, and you will find several daily flights to BKK from all the major European airports should you decide to get there in an Eastern direction. FRA would be a good place to start, with between 2 and 4 daily rotations to BKK courtesy of Thai and Lufthansa. LHR is less of good choice, as the BA aircraft continues to OZ and is frequently full. CPH is a nice transit airport, and if you miss a connection I can point you in the direction of several nice watering holes where you may indulge in the fantastic scenery of beautiful blond girls on bicycles (think short skirts and g-strings here!). No US carrier is presently serving CPH though.
The United flight from NRT is regularly open even in high season.
Good luck; it's extremely hot and humid there at the moment.
METAR: VTBD 011200Z 27008KT 9999 FEW020 SCT120 BKN300 33/26 Q1005 NOSIG (Local time is UTC +7, so 33C/91F at close to midnight local!)