I have a bit of a thing for royalty, particularly English royalty, and most of all, the queens. I've read quite a few fiction and non-fiction books that cover the reign of the Tudors in England, but I've never read a whole biography just of the exceedingly influential and interesting Elizabeth I until I picked up Alison Weir's The Life of Elizabeth I (1998).
This book primarily covers Elizabeth's time as queen of England, starting at the age of 25, although there is some discussion of her early life and her life under the reign of her sister, Mary Tudor. Those interested in more information on Henry VIII and Anne Boleyn (Elizabeth's parents) will have to turn to another book, and although their story is pretty damn interesting, Elizabeth's reign is full enough to fill multiple volumes so Weir made a wise decision to limit the scope of the book.
Weir's book is well researched and very readable -- giving you enough social and political context to understand Elizabeth's actions and motivations, without drowning you in dates, details, and battles. Weir seems to focus more on the personal life of Elizabeth than the political one (although in many cases they are inseparable) and much of the book is devoted to Elizabeth's "will she or won't she" negotiations of marriage.
Beyond the question of marriage, a big focus in Elizabeth's life was her cousin, Mary Queen of Scots, who she corresponded with extensively, imprisoned in England for 17 years, and eventually executed. Since I read a rather comprehensive biography of Mary of a few years ago, it was really fascinating to see their relationship described from the other side.
Overall, Elizabeth comes off as a very smart, funny, vain, powerful, and private woman who kept peace in England for 45 years during a period of religious upheaval in Europe, a task few other sovereigns could handle, and Weir's book provides a comprehensive and engaging look at both the woman and her reign.
Of course, it isn't all fighting the Spanish Armada, flirting with courtiers, and saving Shakespearean theatre from the Puritans. Weir makes sure to throw in some pretty amusing anecdotes. Like the time an Italian pyrotechnics expert had to be dissuaded from shooting live cats and dogs into the air as part of a display honoring a visit by Elizabeth.
Or this one:
When the Earl of Oxford broke wind when bowing before her, he was so ashamed that he went into self-imposed exile for seven years; upon his return, Elizabeth warmly received him, then said, with a mischievous twinkle, 'My Lord, I had forgot the fart.'