Not a student at these schools, but have a 50 year amateur interest in Roman history.
For the sweep of the history of the Monarchy and the Republic there is no substitute for Livy.
For the crisis of the Republic the best source is Appian. The relevant chapters of Plutarch draw great character studies. Caesar and his supporter Sallust explain things from the viewpoint of the populares.
For the Emperors of the 2nd century the best source is Cassius Dio.
Ammianus Marcellinus has some good material from the middle of the fourth century ending at the Battle of Adrianople.
thank you...obviously nothing amateur about your knowledge!