Owen has some very valid points about the difficulty with eating after late-night West Coast departures. You need to pace yourself on your departure day with either more or less meals (depending on how often you usually eat) so that you can last until having dinner at 4:00 am in the East, if you're on SQ 29 LAX-TPE-SIN or SQ 1 SFO-HKG-SIN, both of which leave after midnight West Coast time. The mid-morning arrivals in SIN offer good afternoon connections up to BKK, though you'll probably want a nap the day you arrive in BKK to help re-set the body clock.

The other West Coast flights leave earlier. SQ 11 LAX-NRT-SIN departs around 2:30 pm, but you'll get to SIN late at night and will not be able to connect to BKK until the following morning. SQ 15 SFO-ICN-SIN is also an afternoon departure and gets in late at night. Perhaps oddly, SQ 17 YVR-ICN-SIN flight also leaves in the afternoon. You would need the transit hotel or a night in SIN for any of those options.

SQ 19 LAX-SIN nonstop leaves at 9:00 pm, offering perhaps the best West Coast option in terms of meal timing and jetlag. Skipping the NRT and TPE stops helps a lot with meal timing and jet lag.

The EWR nonstop departs at 11:00 pm, so you just need to pace for a midnight dinner. If you can nap for a short while after dinner, wake up while over Europe or the Pole (depending on routing) and have a snack and a movie or two, then get a full night's sleep at the end of the flight, you'll do okay on arrival into pre-dawn Singapore. The JFK flight also leaves in the evening, and the FRA stop obliges you to wake up, the trick being getting a full night's sleep on the second leg, not the first.