For ladies, of course need to visit the shops of Victoria Secret ..... a lot of choice of bars and underwears. Bath & Body Works is another recommendation (which like body shop but with a lot of choices which are not available in HK). Another definitely need to go is some Factory Outlet where selling a lot of branded clothings at factory cost. Just need to ask your hotel people where is the Factory Outlet close to you. Most of them need to go by driving (so probably need to rent a car for 1 day). Hope this is helpful.
Also, there is a shop named Forever 21 where selling a lot of lady fashion, similar to H&M but at half price. You can visit their website at www.forever21.com
A&F - a commonly found brand in the US. You can find it in all outlets. If you walked in any shop (not in outlets), then the price is less than 20%~30% Hong Kong price. But in outlet, then you will find it is very cheap, talking about US10 for a top.
How about buying some brands that are not available in Hong Kong such as Victoria Secret and Forever 21 (www.forever21.com)?