I don't follow your logic Shado... why shouldn't a visitor simply get a standard Octpous card (not the "tourist" one)? That way they get the "24 hour return" fare on the Airport Express plus the "free connecting MTR" sector. You can also use the Octopus on the Star Ferry and all buses & other ferries. It's so much easier than buying individual tickets. You have to pay a $50 deposit on the card, but you get that back along with the remaining credit on the card when you return it at the airport as you leave (OK - so you have to go down to the arrivals level to do this, but it's no big deal).