I really enjoyed Shamian Island, an area with great food housed in colonial buildings built by the British and the French. You will be spoilt for choice there.
Temple of the Six Banyan Trees is a nice afternoon out, the attraction being the nine story tall pagoda. The grounds itself are beautifully maintained.
The Orchid Garden is a nice sanctuary in the city, there are lovely teahouses there where you can enjoy the tranquility over a cup of tea and some of the city's best dim sum. Exactly what you need after a busy day shopping.
The Canton Tower is home to the world's highest ferris wheel giving you panoramic views of the city. The ferris wheel itself is pretty unique, it is on the roof of the tower around the edges, not for someone who is afraid of heights.
Beijing Rd is a shopping and eating Mecca. The local food is delicious and it's what's most foreigners know to be 'Chinese Food'.
Safe travels! :) almost 8 years ago