Er... Stanley is like so far away from airport. You need to go to Hong Kong station, change to bus that takes you to STanley (or you might need to go to Admirality for bus) and sit on 40 min bus ride. There's nothing to see there, in my opinion. You are far better off going to MongKok's lady street.

Science museum is in Eastern TST and much more accessible. But it's not fun unless you are sciency kind of person, in my opinion... it's like a destination for school tours and nothing comparable to a world-class museum in other city. Having said that, I support the tourism of HK so I do wish you make a visit there and help the HK economy.