u got transport?
if u got, i know alot of places 
take cab also can lah... can go, but the return trip u ownself
settle.
West Coast Park - muchiam pasir ris like that, very fun ah. near to
a 7-11 also, the NUS hostels there.
East Coast Park - cliche lah, but quite steady also ^_^
Jurong Island - abit smelly but very nice views. very VERY VERY
VERY few ppl.
Jurong Hill - overlooks JI, got a very nice chocolate smell, very
nice view as well :p
Changi Coast Road - junction to tanah merah ferry station there.
see aeroplanes, see stars (VERY CLEAR AH!), see commandoes (fit fit
ah!) ^_^
Pebble Bay - tanjong rhu there. overlooking the sea, can see nicoll
highway. very nice place.
Benjamin Sheares Bridge - below the grassy area there, very nice
view of the singapore river and CBD skyline. very chio chio
ah.
confirm no ppl one.
Kranji Dam - can see johor straits and johor night skyline. beware
of crocodiles 
Punggol Pier - nice view of the sea, but quite crowded i think. coz
alot of ppl fishing there. but still very nice.
Seletar Reservoir Upper Zone - ultra ulu, bring stuff there will
form mist, good for teh-teh
the other reservoirs also have.
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vroom...tingtingtingtingti...vroom~