My wife and I have stayed at the YWCA (Fort Canning Lodge) on 3 occasions now, at the end of Orchard Rd and very close to the Museum. Very clean, reasonable food at budget prices, and just all round good value for money. You do have to pay a Membership fee of a few dollars the first time, but you don't have to be a 'Young Woman', and nor will you be subjected to any religious issues. To all intents and purposes at the top end of a middle of the road hotel, but no frills. We booked via
Agoda , as we were offered better deals that way. From memory, we paid about A$90 per night 2 years ago, which covered accomodation and breakfast for the 2 of us for 3 nights in what they call a Superior Twin Room.
When I go back, I shall certainly stay there again. Hope this helps.
PS There is a bus transfer direct from the airport to the Hotel.