Just have a bit-time but want to see how beautiful is Singapore? Why you don't you try the FREE tour while waiting the next-flight like I did. By register at "Singapore Visitors Center", you can enjoy two hours trip to a tourist site.
Just choose what tour do you like. Is it the Colonial Tour, Cultural Tour or a Lifestyle Tour? I think it's better to join the trip than bored waiting five hours for the next-flight. You can also choose the time you want; 10am, 1pm, 3pm, 4pm, 5pm or 6pm.
Try this! You can get memories about Singapore between the journeys, free of charge!