Just a casual, quick show of hands: considering writing on one of these areas under the general heading of traditional Family Law?
Family law is generally a matter for the states. Therefore, when looking for primary law, consider the jurisdiction you are interested in. State laws, cases and administrative material can be found on Westlaw, Lexis, Bloomberg Law or Loislaw.
Valuable information is also available from the judicial and legislative website of each state. Links to each state's official pages can be found here: http://www.usa.gov/Agencies/State-and-Territories.shtml