It's easy to get from the airport to Sydney CBD.... so that shouldn't deter you to stay there. For 2days/1night I would recommend staying in the CBD, as close to the harbour as possible. I was at my hotel in a little over an hour after landing a few weeks ago (with only carry on luggage).
I had quite a nice stay in the Raddisson Blu. Only 5 minutes from the ferry's and trains.