I would like to give you some suggest about the Itinerary：
Day 1: Ocean Park, the Peak, Madame Tussauds, Victoria Harbour, the Symphony of lights, Avenue of Stars, Night Market Temple Street
Day 2: Ngong Ping 360, the Giant Buddha, Disneyland
Day 3: a side tour to Macau
Day 4 : Do some shopping in Hong Kong, especially Central and TST area.
You may find sales in both the two monthes. Weather during the end of April in nice for travelling, warm and pleasant, not to hot.

Thanks Mr David.. thanks alot ~^^~