We are only vacation type flyers, but in Feb flew coach on the LAX-SIN-BKK and SGN-SIN-LAX with SQ for the first time. While I completely enjoyed the Executive Economy flights across the Pacific, my wife did not because of the time spent in the air without a break. I have a "fear of flying" syndrom, so not have to land and takeoff again was a treat for me. We flew in the rear cabin "full" from LAX-SIN and in the front cabin "1/3 empty" (but Business class was sold out?) and particalarly enjoyed the smaller front cabin. The FA were wonderful on all of our flights, though I'm not sure I'd like flying coach on the 777's coach seats we had from SIN-BKK and SGN-SIN... they were ok for the 2 hour flight on both these routes, but 15-18 hrs would be ugh! even with a break... my wife would prefer the break even with tight seats. I'm not sure that would play out in reality for her however. Would I fly SQ again. In a heart beat and is the extra fare worth it... we paid $1500 for the entire flight and normal coach alternatives were in the $1100-1300 range. I'm just sorry that that Executive Economy as we now know it probably has a "short life" with the newer 777-ER's coming out. Well thought I'd add these thoughts from a non professional flyer. By the way the only weak point seemed to be the ground staff at LAX upon arrival.... when we departed they were extremely helpful and courteous. Still courteous on arrival, but seemed more "under staffed" and less helpful... can't seem to get specific except that luggage took forever... but just a general impression.
As a side note we flew Vietnam Airlines for three short legs on our trip and very much enjoyed our flights and service each time... impressed though interestingly they had business class seats on each flight, but because they were short one hour hops they didn't provide Bus class service and kept those seats empty for each flight rather then selling them like Thai Airways did for a modest upgrade price. But very impressed with Vietnam Airlines in any case.