Perhaps it's better to start with "Fortune is a River," as de Grazia assumes a good basis of Florentine history, and his narrative is scattered across Niccolò's life.
From there, you can really get into it and Niccolò's legacy in Pocock's "The Machiavellian Moment. Pocock reeks of the academy, but he serves Niccolò well by placing him before the American republican tradition. Other political scientists, such as (the leftward) Samuel Beer in "To Make a Nation," recognize Niccolò's place but severely limit it.
Niccolò was a magnificent conservative thinker who scares the modern historian.
