For those making multiple rt's, the flight times work better if you start in HKG. It might cost a little more, but by starting in HKG, you don't have to even leave the airport in SIN for the return. You can get a hotel in HKG every other day where you can rest or enjoy the city for almost 30+ hours.
If you have Star Gold status and can print out your return BP online, you can go to the Star Gold lounge in SIN when you arrive early morning.