Star Alliance member Air China offers economy class U fare from Los Angeles LAX to Singapore SIN via Beijing, China PEK for $597 round trip in May 2015. Air China members receive 50% miles for U booking code.
This fare allows an overnight in Beijing on the return with one flight schedule departing Singapore at 9:35am with 3:30pm arrival in Beijing and overnight layover before next day flight at 12 noon and Los Angeles arrival at 9:00am.
Other flight schedules do not require overnight in Beijing.
Air China LAX-Singapore $597
Transpacific flights are on B777 aircraft and Airbus A330 between Beijing and Singapore.
Lowest fares are $583 to $597 in early May 2015 when Air China launches triple daily flights between Los Angeles and Beijing.
There are limited dates with for this fare deal under $600 round trip LAX-SIN. Most dates have fares several hundred dollars higher. Late May offers this route on Air China for about $733.
Los Angeles – Hong Kong on Air China is also available for as low as $572 round trip.