I get out there maybe 3 times a year and usually have to do it as a 2-ticket, with SEA lately the leading break point and, before that, SFO. If You're into mileage maximization you can try routing the SFO-BKK through MSP or even JFK to put the MQM total in the 25-28K range if you can get that both ways.

It's amazing that DL is flying fewer seats in/out of BKK than NW did 10 years ago! (A330s vs. 747s). That's artificially limiting supply, but even if they didn't do that there's the bilateral problem and artificial limits in general to protect THAI and its market share.

If BKK is out of line with other gateways I've also in the past flown into or out of SIN, which is not heard to reach inexpensively from BKK. Sometimes the supply/demand there is more favorable.