Go to Singapore. The only regional airport with more traffic is Bangkok. If you are in a neighboring Malaysia, the option of taking the train or bus to Singapore is pretty straightforward. There are two train lines: the Jungle Railway runs from Kota Bahru to Singapore; the other line is from Penang to Kuala Lumpur to Singapore. Buses will take you there from Kuala Lumpur or Melaka. Ferries can take you from Sumatra or Java to Singapore, but given the time lost, discomfort and expense it is better to pay a little more money and just fly over.
Make the most of the climate. Singapore is tropical, equatorial and does not know the meaning of the word "seasons." It is between 85 to 90 with high humidity and a strong chance of an early-to-late afternoon downpour every single day there. So that is one less thing to worry about: you know what to expect. Beware of the sun, though. Equatorial sun is always dramatically stronger than anyone who has never experienced it expects, and is akin to standing in a microwave.
Try to time your visit for a religious festival. Part of Singapore's cultural melange is that it brings together Chinese Taoist and Buddhist Holidays, Malay Muslim festivals and Indian Hindu observances. Think about it like this: Singapore is a place where Lunar New Year, Diwali and Eid-il-Fitr (or Hari Raya Puasa as the Malays call it) are all big national celebrations. With three calenders to work from, you ought to be able to nudge your trip in the direction of being there for something.
Sample the cuisine. Singapore is a rare place both in its ethnic mix and its comparative wealth. That means there is a lot of magnificent food to be had. The authentic Chinese, Malay and Indian dishes are likely to be made with ingredients superior to what you would find in their native lands. The tropical fruits, such as lichees, lambutans and even the well-known pineapple are outstanding. Indulge your epicure. Don't miss going out into the residential blocks and trying some eats in one of the food courts there. These are not chain food courts like those found in American shopping malls, but instead public centers where small-time food vendors can rent space. The meals are cheap and tasty, and represent the local multi-ethnic every day meals at their best.
Go shopping. Singapore's Orchard Road has a well-deserved reputation for opulent consumerism of the likes that rivals or surpasses that of any other major city in the West. Bring a shopping budget and an empty suitcase, and go to town filling it up with high quality, bargain purchases. Pay particular attention to electronics.
Go to Sentosa Island, Singapore's public theme park, and visit the beach and attractions. One of these is Underwater World, Sinapore's outstanding aquarium.
Tour the particular ethnic neighborhoods, like the British Colonial part of downtown, Little India, Chinatown and Arab Street. This should also include checking out as many different temples as possible, since Singapore brings together the Buddhist, Taoist, Hindu, Muslim and Sikh religions, with just a hint of Christianity.
Do not miss the Singapore Zoo. The primate collection is among the best in the world.
Go relive some colonial decadence at the Raffles Hotel. This institution is named for Singapore's British founder Sir Stamford Raffles, and is a great place to knock back a few late afternoon drinks, drop peanut shells on the floor and imagine you are in a Joseph Conrad novel.
Take a day trip or overnight to Melaka, in Malaysia. It's right over the border and a mere four hours by bus. If you rent a car, you can easily drive there, see some of the sights and return all in one day, all while adding another stamp to your passport.
