Originally Posted by
Swiss Tony
I don't know for sure but I suspect you might struggle to get access into the lounge without a departing boarding pass.
There is an airside transit hotel that would be an option, or you could look for something reasonably priced on your first night in Singapore.
However, given I assume you'll be battling a big time difference the best thing might be just to swallow the cost and head straight into Singapore. It's a very safe 24hr city, so even if you don't want to sleep straight away, there will be things to do.
Sounds like the OP wanted to avoid paying a pricey hotel rate for an additional night when he wouldn't be able to check in until well after midnight.
That's the case when you fly to Hong Kong too, arriving at 11 PM or so.
Can you use the Airside hotels even if you're not flying out the next morning, just want to save some money that arrival night? Then get your luggage and go into the city in the morning?