Mate, you have a tough choice.
If you haven't been to BKK lately, the new airport is still grappling with baggage transfer issues.
Travelling CX and on to KA is a better option though you will be a bit tad too late into HKT. If you are an AA elite (Sapphire / Emerald), you still can get into the CX lounge on the way back. KA will only be in the MPC program in Jan 07.