Do I need a visa? If yes, can I apply a 2 years type as I had helped my kids to apply a 2-year one in May last year for them to go to PRC.

I am a US citienze from Hong Kong. I will visit with my family to Hong Kong and China in July 2014. I have HK Special Administrative Region, Repulse's of Chinese Passport and Hong Kong Permanent Identity Card issued by P.R.C. in San Francisco. I will visit Hong Kong and then mainland in July this year. Thank you.
HENRY CHUNG
Email: hkhkatt.net