The AskHistorians wiki happily points to Thomas Asbridge's book The Crusades: The Authoritative History of the War for the Holy Land which I found both very readable and quite thorough, as much as one volume can be.

Christopher Tyerman's God's War: A New History of the Crusades is less readable - in some parts it's quite a slog - but it's more detailed than Asbridge.

I'd recommend both if you're really interested.

For modern books about the Crusades from a non-Western view I would recommend The Race for Paradise: An Islamic History of the Crusades by Paul M. Cobb, and Byzantium and the Crusades by Jonathan Harris. The Race for Paradise as its subtitle implies is a history of the Crusades from the Islamic perspective and it focuses on how Muslims reacted to Crusades and thought about it in their historiography. For example, Cobb notes that the Muslim world at the time didn't think the Crusades started with the First Crusade but with "Frankish" attacks on Islamic Sicily.

Harris's Byzantium and the Crusades on the other hand is about the Crusades and their relationship with the Byzantine Empire. It begins with a brief history the Byzantine Empire during the 11th century and its society and ends around the end of the 13th and beginning of the 14th centuries when the last Crusader strongholds on the mainland of the Levant were regained by the Muslims.

If you want primary sources I would recommend Penguin Classics' Chronicle of the Crusades which contains Geoffrey de Villehardouin's The Conquest of Constantinople, an account of the Fourth Crusade against Byzantium, and John de Joinville's Life of Saint Louis, a history/hagiography of the French crusading King Louis IX who embarked on the Seventh and Eighth Crusades. I found them to not to dry and an easy read.