Oscar's Conrad Hotel Great place to chill out over a humongous plate of fried rice and coffee after partying all night. Open 24 hours. Expensive and overrated, but if you're looking for a nice, air-conditioned and quiet place to wind down at 3am, it's not too bad. The best location on Orchard Road for people watching in the day, although some beautiful people do flock there on weekend nights. Alfresco sitting great for smokers and the satay is quite nice.
Food is good and service is prompt.
Open till 1am on weekdays and 4am on weekends. Pasta Fresca 30 Boat Quay Convenient if you're at Boat Quay at 3am and craving pasta, but not much attraction other wise.