(November 2015 and other "visa runs")
It is not just about SIngapore. It is also about Changi. I really do love this airport with its butterly gardens, napping area and the best pork ribs in the whole world! Literally :D So visiting Singapore as a visa run is always a pleasure, same as doing just a stop over there. (Oh, sorry, I also forgot to mention the proper coffee, not the instant powder you get on all Asian islands only.)
Singapore is, same as Kuala Lumpur, a place you feel "back in civilization", after you spend few months in real Asian paradise far from everything.
If you are in Singapore, don't miss the famous and supermodern Marina. That place can keep you busy for almost whole day, easily. Ferris will will fly you over the city/country and you can decide what to do next. Walking around is definitely worth it. If you head to the park, with the giant flower trees, and you will feel like you are in Avatar for a while. Save some time to walk over the bridge and don't miss the view to all new development, which has its own specific beauty.
As I have mentioned already, pay a visit to as many different restaurants as you can, but be careful, as the close after the lunch. You can choose between variety of international cuisine, but the sea food and fish are highly reccommended.
If you are lucky to spend a night in Singapore, make another small trip through the modern part, as the light show and lightening is just awesome.