Arriving at HKIA with 4 large bags and 2 small ones. What's the best way to hotel grand, kowloon?

Oh, you must refer to Harbour Grand Kowloon, right?
Upon landing, you can take bus no.E23 at Airport (Ground Transportation Centre), get off at Whampoa Garden. It takes around 70 mins on the way. And the ticket fare is 18 HKD per person. There are enough space on the bus that can put your luggage. So don't worry.
After arriving, walk southeast around 300 yards to find the destination. :-)