I used to fly Thai Air on its now-discontinued non-stop JFK to BKK in premium economy and loved it. But that was then. These days I fly Korean Air economy IAD-ICN-BKK - current lowest price $1420 - two or three times a year and find it almost as good. Korean also flies out of JFK. The seats have a decent 34" pitch and a very up-to-date inflight entertainment system. (EVA's premium economy has 38" pitch.) It's not a perfect solution, but with business class at $4K-$5K, I've found it to be an economical compromise. The $2500-$3500 savings goes a long way in Thailand.