Economy seating on Thai's Boeing 777-200 is in a 3-3-3 configuration (A,B,C - D,E,F - H,J,K). The only exit row on this aircraft in economy is row 50, but row 31 provides bulkhead seating and the pairs of seats by the windows may be attractive.

Further back, from row 60 onwards, configuration becomes 2-3-2, so consider these seats also, but remember that the very last rows are by the washrooms.