I know I've written a time or two here about "What it Takes," by Richard Ben Cramer. It's an exhaustive account of the 1988 Presidential election campaign, with a page count that gets into four-digit land.
But the amazing thing is that it's all awesome. It's not one of those massive books that makes you wish it had been edited better, and that you just keep reading out of a sense of commitment. Instead, it's a magnum opus that addresses a myriad of contemporary American issues of all sorts, and gives revealing and meaningful biographical information about a lot of people who still loom large on the contemporary political landscape (like our current Vice President).
A buddy of mine sent me this link, which talks about how the book was not initially well-received, but has sort of flavored with age and developed a following among people who've discovered it at used bookstores (like I did) and fallen in love with it.
If you have the time and the dedication, check out "What it Takes."