Most people pick up a little knowledge about the Louisiana Purchase in their trip through school — Napoleon needed money, Jefferson wanted land, they made a deal.
If you want to go a little deeper than that — without being overwhelmed — then you should pick up Jefferson's Great Gamble, by Charles Cerami. Its 300 pages look at both the people and the issues involved in deciding the ownership of about one quarter of the continental United States.
The people involved weren't just footnotes in history either. On the American side, you had President Thomas Jefferson, who was the prime mover in getting Louisiana. You had Secretary of State James Madison, who would become the next president. The Extraordinary Envoy to France during the negotiations was James Monroe, who became the fifth president. Right there you have the author of the Declaration of Independence, one of the primary authors of the Constitution, and the author of a famous Doctrine. The fourth player on the US side was our Minister to France, Robert Livingston of New York, who served in the Continental Congress, and was on the committee that helped Jefferson write the Declaration of Independence.
On the French side was Napoleon. By this time he was already a successful general, and was bringing order back to post-Revolutionary France. His Foreign Minister was the famous Tallyrand (some might say infamous).
The initial negotiations were only over New Orleans, which could either facilitate or hinder the movement of goods from the vast Mississippi-Ohio-Missouri River watershed to the rest of the world. To make negotiations even more complicated, New Orleans had temporarily been a Spanish possession, and Spain still had claims on the area. The British up in Canada also had more than a passing interest in possessing the city, too.
Reading the book, you are struck by the notion of how some things don't change:
We were unsure of our relationship with France: They had been our allies in our Revolution, but the details of their Revolution turned off a lot of Americans (that whole guillotine thing.). We weren't exactly sure about Napoleon, either. He was still new, and just First Counsel in addition to being a successful general.
Bureaucratic infighting in the State Department: Of course, it was a much smaller State Department, maybe a couple dozen people. The division here was between Jefferson and Madison on one side, and Robert Livingston, the American Minister (ambassador) to France, who was a holdover from the Federalist Administration of John Adams.