Originally Posted by jpatokal

I'm not sure I'd agree with that. Sure, you aren't going to see the whole city in 6 hours, but that should still give you an easy 3 hours to poke around, say, Chinatown or Orchard Rd and have a nice meal somewhere. The MRT is cheap and easy to navigate (30-40 min to city), and using a taxi won't cost much more and will save another half an hour's worth of time for a round trip.