Haikou

Haikou is a fairly large tropical coastal city. Haikou has a different vibe to many cities on the Chinese mainland. The tropical climate is probably a major influence on the laid-back atmosphere. Whereas on the mainland many cars drive too fast, in Haikou many drive too slowly. The local man has a reputation for being somewhat lazy and can be seen sleeping in the street during the afternoon and then playing cards with friends until the small hours of the night. Silk pajamas can be seen worn during the day and add to the atmosphere. You will not be hassled to buy anything which makes a refreshing change to more touristy cities.
Many streets in Haikou are quite different during the day compared to the evening. Small outdoor restaurants and stalls fill the streets in the evening and many areas are at their busiest from 9PM to 1AM. Local favorites are BBQ stalls which serve cheap local beer till late.
You will soon notice the abundance of coconut trees within Haikou. Most streets are lined with them. Its greener than most Chinese cities and has decent air quality.

By Plane:

Haikou is a transport hub with flights to many cities and boats to nearby mainland cities such as beihai and zhanjiang. Tiger Airways now flies from Singapore and Air Asia to Kuala Lumpur.

By train

There is a train link between Haikou and Guangdong province (the trains are loaded onto ferries to cross the sea). So you can get the train from Guangzhou to Haikou. The trains actually start and finish in Sanya, but it takes about an hour by bus to get from downtown to the train station, and the train station in Sanya is also far from that city's downtown area.

By bus

Buses connect Haikou to many cities on the Chinese mainland, including Guangzhou, Hong Kong, Shenzhen, Guilin, and Nanning. Most buses are overnight sleepers. Buses are loaded on to ferries and arrive in Haikou at either Xingang port or Xiuying port. Here's a few examples showing journey duration and price.