As for where to stay, I'm not qualified to comment, so I will pass.

What to do?... personally, what with a late night arrival, and limited time the following day, I would attempt no more than:

1. Get up nice and late.
2. A return ferry crossing (a must if it is your first visit to HKG).
3. An easy trip to the airport.
4. Enjoy the CX lounge.

But then that's just me... others will sure differ.