Have you checked the NARA site? They list the resources that are available. That being said....The NARA has a lot of records. It is best to inform yourself as to what records are available through the NARA. Go with a research plan. If you are like me, it would be like releasing a kid in a candy store, if you don't have one you may go from one record to another without any rhyme or reason. I would also concentrate on records that you cannot get access to otherwise.

Here is the site for NARA:

http://www.archives.gov/

Good luck.
Sandra