If flying through BHD then the local train can be the quickest option to the hotel at peak times. BHD provides a free min-bus to local train station Sydenham at a corner of the airport (ask at airport information desk)and it is only one stop then to Central, the other way buy ticket to Sydenham and cross bridge to airport side entrance and use the yellow phone to call the min-bus.
I usually do this. I wouldn't recommend it to visitors with baggage, or if it's raining, or, to be honest, to anyone who would not class himself as an intrepid traveller. You get dropped off at a back entrance to the airport and need to go up a long staircase (equivalent to 3 storeys) and across a busy road bridge, before going down on the other side to get to the station.