I fly from Atlanta to BKK several times each year. I fly Qatar, Cathay Pacific, Turkish Airlines and, when on sale, Delta. Occasionally I find great deals using “multiple airlines” option in Skyscanner or Expedia
I am not sure how it relates going from USA to Thailand and back, but I got round trip tickets from Qatar airways for about $1200 usd. The key factor was it is with 60 days advance purchase. I did this last week.