For your air ticket to Sanya, we would suggest you consult the websites below:
Air China: http://www.airchina.com.cn/en/
Hainan Airlines: http://global.hnair.com/
China Southern Airlines: http://www.csair.com/en/index.shtml
China Eastern: http://en.ceair.com/
Cathay Pacific: http://www.cathaypacific.com/
About the visa: We would suggest that you apply for a tourist visa. If you need a formal invitation letter, please send an email to firstname.lastname@example.org.