I've done the bus - HK is not a scenic ride into the city - unless you like seeing apartment buildings with laundry drying on every balcony. The sights are once you get there. Thus, use the Airport Express, get there much, much faster, and enjoy this great city. The only thing I might suggest different than some is to stop first at Kowloon so you can see across the Harbor to HK Island. But with as many hrs as the OP has, I'm sure he/she can enjoy both sides.