Yes... the market by the White Swan will really give you a taste of China... That would be my #1 recommendation.
I LOVE Guangzhou, have been there about 6 times. In one day you will likely only do tourist things. *DO* have a tour as opposed to trying to do anything on your own. GZ trivia - the surface area of the cars there is greater than the surface area of the total roads... can you say gridlock? And yes, the train ride from HK to GZ is a rich experience. IMHO, GZ is much mor *China* than Shenzhen and worth the extra travel time. (I think Macau is a dump.)