Jonathan Gould, Can't Buy Me Love: The Beatles, Britain, and American (2008)
Gould, a musician and a fan, provides the sort of group biography that many readers look for. But he also offers an insightful analysis of the music, the songwriters, and the social and cultural context that shaped both.
Bob Spitz, The Beatles: The Biography (2006)
The title is a bit pretentious but this is the most comprehensive biography of the band. It's not for the faint of heart—at close to 1,000 pages, you have to really want it. But Spitz, a regular contributor to the The New York Times, writes well enough to make the tome manageable.