ANA and United have round-trip flights from Houston (IAH) to Bangkok (BKK) for $555. Flights sparse and scattered from late-March to May. Holiday Blackouts apply. 7-day minimum stay required.
Note: Fare allows for a stopover in Japan for +$120 more. If you’re wanting to spend a few days (or weeks) in Japan before going to Bangkok, consider doing IAH-NRT-s-BKK-IAH. Example screenshot below.
Note: ANA tends to have better service and cabins than UA.