OK, this isn't much of a contribution, but here goes: I have flown GA between CGK and BKK a handful of times in C class and have found it perfectly acceptable. The service would never be confused with that of TG or SQ, but for someone who usually flys NW WBC transpac, it was friendly and attentive by comparison (and you can accrue NW base miles). The front cabins on their 737-400 are positively spacious. I have never seen a seatmap for this plane so I don't know what the pitch is, but it has to be at least 40 inches. I have never been on a 737 with this much room in the front.