Originally Posted by
ajnz
...Both close overnight...
The Krisflyer Gold lounge in T3 is open 24 hours. I was there last night at 1 am and confirmed this specifically with the desk agent, who also apologized for the slim selection of food at that hour but urged me to return for breakfast.
That said, it still has no showers, only semi-comfortable armchairs to stretch out in, and a fairly high light level throughout. A six-hour block at the transit hotel is about S$70, or a bit over US$50. I'd go that route. Last night the T3 transit hotel had walk-up availability.