Also note that the SQ flight via BKK has (I think) the regional C seats and therefore is probably not as good as Club ANA Asia (which itself isn't great). Best option for seat comfort (although not overnight) is SQ12 (or is it 11?) that is operated by the 747 and likely to be 77W (new seats) soon.
If you are considering taking the via BKK flight then consider flying TG as an alternative option.