The best thing about Singapore is that it's an architectural park with a focus on amalgamating greenery into urban life. The modern city-state is enthralling and well developed with quirky skyscrapers, diverse communities and unique buildings. The experience I've had, has been a science fiction turned reality.
After reaching Singapore and hotel check-in, if you have got time start exploring the city. Best way to explore the city is to travel by metro to avoid traffic. It is cheap, and reasonable and the whole city is connected by MRT route. Find a MRT station and collect the route map and hop on to a metro.
Get off at Bugis Junction, Masjid Sultan is at walking distance. Enjoy artistic buildings at Haji Lane. Reach MRT station, and get down at China Town MRT station to visit Buddha Tooth Relic Temple Museum and Sri Mariamman Temple.
Take a metro and reach Harbourfront. Take a bus to reach Sentosa Island. Spend the whole evening at Universal Studios and S.E.A Aquarium.
On Day 2, take the MRT route and get off at Raffles Place station. Enter the famous Merlion Park, take a walk to the other side through the helix bridge and visit ArtScience Museum to experience surrealism. After that, walk through the Gardens By The Bay and visit Cloud Forest and Flower Dome. Take a walk to the SuperTree Groves in the evening, wait for the sky to become dark. The whole place lights up at night and the lights dance according to the music.
After the light show is over, take a walk again to the Merlion Park, and be amazed to see a spaceship has landed over the roof top of Marina Bay Sands.