Just curious, but you do realize that the SQ bargain fares do NOT earn FF miles in any program right? So unless you have some other reason to fly to SIN for only 11 hours, you may want to change that!

That said, there is plenty to do in SIN for 11 hours. Depending on the time of day you can either take the MRT or a cab into town for food, shopping, etc...

Heck, that's enough time to head across the border to Malaysia (MRT to Kranji station , 170 bus to Johor Bahru) or to Indonesia (MRT to City Hall, free shuttle to World Trade Center, ferry to Batam).

There is a left luggage available in Terminal 2 just to the right of the MRT escalators by the taxi stand. It was open last time I was through Changi on Saturday.