Originally Posted by bgriff

If you book just LAX-NRT on SQ.com, you are eligible for a 15% discount on the number of miles quoted for that award, whereas if you involve a UA flight NY-LA you would have to call SQ and would not be eligible for the 15% discount (and would also have to use the Star Alliance award chart, which may cost a bit more).

You would also have to find UA award availability for the date you want, which may not be easy.

However, if you decide to book a cheap flight separately, keep in mind that you need to leave time to check in with SQ at LAX, and to claim and recheck baggage if you're traveling with bags, plus you may be SOL if your first flight is delayed and you miss the SQ check-in deadline. Whereas if you are all on one ticket and you miss the connection, SQ is obligated to reaccommodate you the next day or on another airline.

Personally given the SQ departure time and options for NY-LA flights I would probably choose a flight coming into LA the night before, in which case you have to pay for a hotel room ... so up to you how you feel about the extra hassle.