My experience with Pizza Hut is quite good. I've spent $2,500 for around 40 persons. The restaurant is spacious and the waitresses are friendly to the kids. We had a good time there. The Pizza Hut is at Causeway Bay.
The kids are around 4-5 year old and they did enjoy party. My party's schedule is :
3:30-3:45 Wait for guest
3:45 Start serving food (buffet)
3:50-4:00 Making Pizza (for kids)
4:00-4:15 Games (1st round, around 2 games)
4:25 B'day cake cutting
4:40 Games (2nd round)
4:50 Dessert
5:00 Party end
It's a bit rush but it should be enough for the kids of that age group. You can decide on your own schedule and ask Pizza Hut to follow.