There are two hip, cool boutique-rich streets in Singapore that are worth a visit. Club Street near Chinatown has some very cool boutiques including StyleNordic, Asylum and Books Actually -- plus some great restaurants for a lunch break. Haji Lane near Bugis is a back-alley type of street that houses a bunch of very hip designer shops -- designer and vintage clothing and accessories, jewelry -- with art, rugs and houswares thrown in.
If you want an all-in-one shopping experience, Paragon and Takashimaya, 2 malls facing eachother on Orchard Road, offer something for everyone. In Paragon, lunch at Din Tai Fung for Dim Sum (basement) or PS Cafe (second floor) for great salads, sandwiches and other western food.