Dont forget Garden by the bay, u probably appreciate more after u watched Megastructure program on it by National Geography.
street foods are extremely clean here, just like HK.
Singapore street food is generally very clean and hygienic. there are big signs at the side of every food stall with "A" or "B" or "C" whereby "A" is judged by the authorities as the most hygienic food preparation possible. It is very unlike the street food here in HK whereby dishes are washed in the drains along the roadside or back alleys. As a Singaporean, I am very careful to avoid streetfood here in HK, as well as most of Asia. Use this for local recommendations: Singapore Hawker Food - Top hawker stalls in Singapore & Hawker food reviews - inSing.com
1. little india - probably one of the few authentic places left in singapore. besides soaking in the bustling atmosphere, you can have indian vegetarian food (gokul is good), fish head curry or get a henna tattoo.
2. kampung glam - laid-back malay/arab enclave (you can walk there from little india). nice in the evening.
3. pulau ubin. have your meal at changi village hawker centre (there are two famous nasi lemak stalls there) before/after that.
4. joo chiat - great variety of food within minutes of each other, e.g. chin mee chin kopitiam, janggung laksa, otak-otak. plus lots of local/western dessert stores. and also peranakan architecture/culture. to burn off those calories, stroll/cycle along east coast park after that.
5. geylang serai market/food centre. cheap and good malay food. the wet market on the ground floor is very interesting. (this is within walking distance of joo chiat)
6. geylang by night
7. botanical gardens. maybe followed by dinner/drinks at dempsey?
8. take a walk around an hdb estate eg toa payoh, ang mo kio to see how most locals live
9. if you're into trying out new brunch places, here's a good list to start with:
Best Brunch in Singapore | ladyironchef - Singapore Food Blog
10. night safari
11. gardens by the bay? haven't been there yet so can't give a comment, but it has received a mixed range of reviews.
12. any hawker centre would usually have a range of malay/chinese/indian/singaporean food/drinks for you to try. you could consider maxwell (tanjong pagar) or smith street (chinatown). or if you're around town, lau pa sat or gluttons by the bay at the esplanade.