As far as I know, Hong Kong is a really good place to watch the races.
Here is a schedule for Hong Kong from May 10-28th. This includes all the islands as well around Hong Kong:

http://www.discoverhongkong.com/eng/events/images/sports-2009_local_dragon_boat.pdf

According the LP Thorntree:

24th May - Zhuhai
28th May - Zhanjiang
30th-31st May - Nanning
6th June - Guangzhou

Hope this helps.

On May 28th, Suzhou River Dragon Boat Race will be held on the Putuo section of Suzhou River between Jiangning Road Bridge and Canghua Road Bridge. Besides the race itself, there will be various traditional song and dance performances.

Furthermore, the first China Charitable Equestrian Carnival will take place on the same day. At that time, you could enjoy not only exciting polo game, but also horse-racing, in which twenty amateur riders will participate. Complimentary equestrian Carnival tickets will be available for the cost of donations, and all proceeds will be donated to public welfare.

The first China Charitable Equestrian Carnival will take place at the Ping Lake Jiulong Mountain Resort in Zhejiang Province. Six polo teams, which come from Germany, Italy, Argentina and so on, will have an exciting Polo race.

So happy to see that there will be Dragon Boat Race in Suzhou. Several of us are coming down from Jinan to enjoy this festival and take in some of the Suzhou parks and beautifies.

Do you have a time schedule for the Dragon Boat Race? We fly in to Hongqiao at 9:30 am and should get in to Suzhou at noon on May 28. Hopefully we will catch some of the events.

Thanks in advance for the information.

Shirley