Yes TG might be government owned but they pack those planes up to the gills. Plan with caution as BKK along with SIN are known as a black wholes for nonrevs, at least the LAX-BKK is usually full and intra asia flights on TG have very healthy loads as well. I also know with TG you list through FLYZED.com, I would recommend following up with a phone call thorugh treir rez center to vrify you are listed as somestimes listings through that website can fall through.
Since you are DL and you guys have such a big hub in NRT i would recommend connecting through Tokyo. There you have options on NH, DL, UAL, JL and TG.