Everybody on this blog is publishing stuff lately. The scholar formerly known as Gina Russo, now known as Gina Russo Tam, has a nice review up on the archives of Guangzhou. So if you want to plan a trip, this would be helpful.
For what it is worth, this is one of the most valuable features of the very valuable Dissertation Reviews. Chinese archives change constantly, and this sort of post is one of the best ways to find out what is up before you go. With any luck Gina will post something soon on cool things she found in the archives.