Contacts:

Location: Swissôtel The Stamford, 2 Stamford Rd., Colonial Singapore, Singapore
Ph: 6431-5681; 6837-3322
Hours: Sun.-Wed. 3 pm-1 am, Thurs.-Sat. 3 pm-3 am

The New Asia Bar  is probably the best place for sundowners with happy hours extending till 8 PM. This is where your nightlife can get a really exciting! This bar is located on the 71st floor of the Swissotel Stamford. Two floors of bar space, magnificent views of the city and its skyline and a fashionable clientele are what you should expect here.

Even the floors are angled at a 20 degree slant to give you a fabulous experience! The DJ here is awesome and so is the collection of drinks and cocktails in particular. People frequent this place as much for the view and the experience as is for the drinks.

View Singapore @ New Asia Bar (Source: Chantal Boogers) 

Here is a remark from a visitor

New Asia Bar is definetely one of the most unique and exclusive bars in Singapore. A panorama view over down town Singapore in the tallest hotel in Southeast Asia makes it worth a visit. Especially when the so called "heli-pad parties" is on. The party starts at the Heli-pad at the roof top of the building and continues inside the bar with DJ's.

 (Source: Momondo - Flight Search Engine)

Another person says

If you visit Singapore and are looking for a special//memorable evening , then this is the place to go. I found it quite hard to find (it's on the 71st floor of the Stamford hotel, you need to go up a special elevator from the ground floor entrance of the shopping plaza - ask one of the employees if you're not sure and they'll be happy to help.).

You may need to reserve a table on busy evenings. Basically, this bar does what you'd expect - it's classy, pricey, and commands spectacular views north .The bar atmosphere is "chilled out" and modern, quite dark with coloured mood lighting, and feels like a slightly more atmospheric bar in a nice hotel.

new asia bar, Singapore  (Source: TripAdvisor)

Contacts:

Location: 17 Jiak Kim St., Robertson Quay, Singapore
Ph: 6738-2988
Hours: Wine bar: Sun.-Mon. 6 pm-1 am, Tues.-Sat 6 pm-3 am; Velvet Underground: Tues.-Thurs. 9 pm-3 am, Fri. and Sat. 9 pm-4 am, closed Sun. and Mon.; Zouk/Phuture Weds. 9 pm-3 am, Fri. and Sat. 9 pm-4 am, closed Mon., Tues., Thurs., and Sun.

Tiger Beer from Singapore (Source: William Cho) 

The Zouk club is actually made up of 4 hot venues, namely Zouk, Velvet Underground, Wine Bar and Phuture - each catering to different tastes! Established in 1991, this club has been consistently getting rave reviews and is considered to be on par with several other globally reputed clubs. A party-goer shares

if you are in Singapore and if you miss out the nightlife, then i would say, stay one more night and freak out!
Zouk, is a place to be at. Cool music, cool babes and the whole cosmo-Singapore comes to life at this place, you will find people from all over the world, hanging around.
Hence, if you are in Singapore, don't miss this out...Zouk is a place to be at !!

Zouk Club, Singapore (Source:VirtualTourist)

Yet another person says

Zouk is THE pub/bar to party and chill out. Break free from boredome and hangout with your friends. They play great music tunes- techno, pop/rock and some remix. Sometimes when there are events, they'll set up a temporary stage to hold performances. It's great here, come join the party!

Zouk - Singapore (Source: TripAdvisor)

Contacts:

Location: 28 Boat Quay, Boat Quay, Singapore
Ph: 6538-3029
Hours: Sun.-Thurs. 11 am-1 am, Fri. and Sat. 11 am-2 am

. (Source:.) 

Harry's Quayside Bar is a fascinating place by the water for Jazz, Blues and Rock fans. They have a number of locations scattered throughout Singapore but the Boat Quay joint is highly favored by one and all! Here is what a traveler has to say

Been there last Sunday and the jazz jamming was amazing. The spectrum of instruments played was awesome and the musicians came from all over including Latin America and local Singapore. If you are in Singapore and love jazz, this place is a MUST on your itinerary.

Harry's Bar - Singapore (Source: Yahoo! Travel)

Contacts:

Location: 3 Sentosa Gateway #01-01 Sentosa Island, Singapore
Ph: 65 6270 7676

Hours: Mon. - Fri. 6 am to 6 pm./ Sat. & Sun. - Closed.

St James Power Station, The Current Hot Spot in Singapore (Source: William Cho) 

St.James Power Station is a renovated coal power station which is now an all-in-one entertainment complex situated in Sentosa. It houses several distinctive outlets, each with it's own signature style. A short note in what to expect here

Over 70,000 square feet (6500 square meters) of nightlife shenanigans in a nattily refurbished power plant. If you can't decide whether you want loud pumping beats, some intimate jazz or to DIY with some karaoke, no worries - with the one cover charge, you can head to any of the 11 venues. Wiggle that booty at the Latin-themed Movida, dance up a storm to club anthems at Powerhouse, or escape to the Bellini Room for some top-notch live jazz and soul.

St James Power Station: Singapore (Source: 10Best Experts and Tourist Reviews)

Contacts:

Location: Chijmes, 30 Victoria Street, Singapore

Ph:187996 +65 6338 6883

Hours: All Day.

Dirty Martini (Source: Evan Swigart) 

If you are looking to party all day and all night, then Insomnia is the place for you! As the name implies this a venue that operates 24/7. Live contemporary and rock music is played at night by different bands. They have a busy dance floor as well as outside seating. A comment from a visitor

Short time in Singapore, was incredible time however Insomnia - was the cherry on the top for me! In fact, I'm booking my next flight and you bet ya, Insomnia is definately on my 'to do again' list! Top marks Insomnia

Insomnia Review, Singapore (Source:Thursday Club)