I fly out of BKK often. I find TG very helpful. They have a special desk for staff check-in, which all non-revs should use. I usually take the red-eye to NRT, which always has lots of seats. Unfortunately, I have no experience with the non-stop out of BKK to LAX. Use FLYZED to check the availability of TG. You can also list for TG on FLY ZED. Hope this helps a little.