from the top of my head
sunrise:
punggol end beach
changi beach
any reservoir, but you have recee location
merlion park
sunset:
chinese gardens (twin pagoda or the lake)
changi boardwalk
punggol end beach
most reservoirs
shenton way skyline from esplanade riverside
labrador park
raffles marina
kallang basin area (not sure now though, i see some works going on)