As an initial matter, it is important to remember that most legal disputes are resolved in state courts, which are the primary fora for contract disputes, tort claims, criminal prosecutions, divorce and custody matters, and probate of estates. While the substantive law you may encounter in federal courts is by no means narrow, it is even broader in state courts.
If you talk to someone who has clerked for both a federal judge and a state supreme court justice, you almost invariably will be told that the latter was the more interesting clerkship. Why? State supreme courts are most often courts of discretionary review; this allows the justices to "cherry pick" the most interesting cases to settle important questions of law. In addition, since supreme courts are the states' highest courts, they have tremendous ability to influence and shape state law. Apart from these considerations, a state supreme court clerk's tasks largely mirror those of a federal appellate court clerk.
Intermediate Appellate Courts
Not all states have intermediate appellate courts, and the quality of the court and duties of the clerks can vary greatly. The nature of the work, however, is quite similar to that of federal courts of appeals.
Students who know they want to settle in a particular geographic location should consider applying for state trial court clerkships. These positions provide an unparalleled opportunity for students to get to know, and become known by, members of the local bar; usually, clerks in these positions have far more contact with attorneys and court staff than is typical in the federal court system. Further, these clerkships provide an excellent opportunity for learning state rules of civil procedure, as well as substantive state law. While state court trial judges typically do not publish opinions, their clerks will research legal issues (often on short notice, such as during trial), advise the judge on rulings, draft orders and rulings, and observe and assist at trials.