You can read my Hong Kong Day 1 experience in my other post
HERE,
I'll be posting details of my Day 2 to Day 4 experience soon.
But off hand, other things you could do are,
1. Visit Disneyland (1day)
2. Shop at Ladies Street (cheap goods, but need to bargain)
3. Visit Golden Bauhinia... this is a "new" landmark built after HK
was returned to China.
4. And of course, eat lots of tim sum.