You have to restrain places that you want to go, i would recommend you to go to Beijing, Shanghai, Xi'an and Hong Kong. I have been to all this places I would say these are the places that i like the most
Beijing is a great place where there is a lot to see such as great wall, summer palace, forbidden city, Tiananmen Square, the Qianmen Gate, National Stadium (Bird's Nest),Temple of Heaven etc, you have to go to Beijing if youre going to China.
Shanghai- EXPO, Shanghai Happy Valley, Jinjiang Amusement Park, Shanghai City Beach, Jinshan Donglin temple etc
Xi'an- ancient city wall, Shaanxi Provincial Museum, Forest of Steles, Wolong Temple, Big (Wild) Goose Pagoda, Eight Immortals Temple, Grand Mosque, Bell Towers and drum towers, China South City (Best shopping place) i would recommend to spend a day in China South City, it is logistics trading hub which impressed me a lot
Hong Kong- Peak (prettiest view), Disneyland, Ocean Park, Tst victoria Harbor(light show), nathan street Mk night market ladies street (cheap bargain stuff), causeway bay, laiGuifung (clubbing street)...Hong Kong is a very international place and things there are really cheap too if youre looking for fashionable clothes, shoes, electronics, purses etc, im pretty sure you can find a really cheap hostel to stay in Hong Kong.
hope this helps!
