I might as well include these books on this list because for the past two years I've been in the slow process of reading five different biographies of Charles Dickens:
1. K. J. Fielding, Charles Dickens: A Critical Introduction (1965)
2. Fred Kaplan, Dickens: A Biography (1988)
3. Stephen Leacock, Charles Dickens (1933)
4. Edgar Johnson, Charles Dickens: His Tragedy and Triumph (two volumes, 1952)
5. Peter Ackroyd, Dickens (1990)
As I continue reading and teaching the complete novels of Dickens with my ongoing Newberry project, I find that I've settled into a pretty solid routine when writing my lecture notes on Dickens's biography.
For each pair of novels I teach (e.g., the 1849 - 1853 period that comprises the publications of David Copperfield and Bleak House), I read the appropriate sections of each biography in turn and take notes as I go. I then organize those notes into the appropriate number of sessions devoted to each book, and type up the notes accordingly. At the moment, I'm about halfway through each biography.
I usually begin with the Ackroyd and Johnson biographies because of their abundance of detail. I'm able to get most of my lecture material from those two, followed by the Kaplan bio (which is actually getting better now with the mid-point in Dickens's career). I then fill in the details by reading the Fielding and Leacock biographies which, though they aren't very engaging and are mostly cursory, provide a few anecdotes here and there. If time permits, I might return to scan each book in the weeks prior to the start of a seminar to ensure I have all the biographical info I need.
Of the five, I'd recommend the Peter Ackroyd biography to anyone who's interested in reading an entertaining and informative account of the life of Charles Dickens. It's the best of the five.