I think you are on the wrong track. But of course it is your call!
In my view you need to rethink your taxi limitation. It is making your choice of hotels and location to me odd.
Taxis are almost free, taxi drivers are almost all honest and easy, and everything is a few minutes away in a taxi. This limitation you specify is making your life more difficult than it need be. I wouldn't want to stay in a hotel on Orchard or anywhere simply to avoid taxis. It makes absolutely no sense to me.
Just suggest you pause and re-think .......
If not then Intercontinetal at Bugis. So much close by 24 hours per day.