I was just wondering if Runciman's multi-volume work is still considered the definitive history of the Crusades? I read the first volume a few years back and I remember being impressed with the detail but disappointed with the lack of analysis.
Are there any newer books which investigate the Crusades in great depth? The only other book I know is the one by Jonathan Riley Smith.
Runciman's work is most definitely dated at this point. I assume from the question that you are looking for a general survey of crusading overall. Two major introductory surveys by contemporary scholars which you could try are Thomas Asbridge's The Crusades (subtitled either: The War for the Holy Land or The Authoritative History etc. in the UK and US versions respectively) and Christopher Tyerman's God's War: A New History of the Crusades. (Riley Smith has also written a fairly recent survey, but I assume that is what you are motioning towards.)
If you are looking for greater depth than a survey text generally, you will likely need to be more specific about what topics you are interested in.