Dr.Arul,Saudi Arabia,Query on Octopus Card Utility!

Would be reaching HK on 29.08.2012.Have to travel to HK station,nearby,where I would be staying.Again have to travel to Airport on 30.08.2012 for picking up my wife & again travel to HK station,for staying in my accommodation. We would be in HK for 3-4 days roaming/sightseeing & would be departing together from HK on 03.09.2012 by flight. So plz. let me know whether to purchase individual up & down round trip airport express tickets plus Octopus card (Airport Express) travel pass for local travel (OR) only individual Octopus card will be enough to cover all these.