Hi jeklah, if you only have 24hours, my suggestion is for you to do a organised tour. They come in morning and afternoon formats. The evening zoo tour is fantastic. The hotel will book this for you, it will not cost anymore. Try to book a hotel in a busy area as against out of the way. Preferable to pay an exrtra $100 and be right in the action if the legs aren't working like they used to. It's so pleasant to walk out of the hotel and prop at a coffee shop and watch the world go by, you can spend an enjoyable couple of hours in Singapore doing just that, you have a good time!, you are only here once. What is the name of the hotel on the corner, is it the Marriott, you cannot possibly get anymore central in Singapore and the coffee shop on the corner is not cheap as I recall, but who cares!
The taxis from the airport are easy, no need for a transfer, unless you like the idea of someone meeting you at the exit. The train/ subway sytem is easy to master also, and there are stops along Orchard Road. Take the underground to CityHall, upstairs are shops and hotels. My call for you would be an Orchard Road hotel, pick your favourite hotel brand, it's sure to be there, regards bkkrop