Of the 3 books I recommended, The Proud Toweris more of a lead up to the war, rather than the war itself. Dreadnoughtis very detailed and not as easy to read for some, but I personally loved reading it anyway. I liked it even more than the Tuchman duo, but it is well over 700 pages as I recall.

He doesn't get into root causes much, but he explains campaigns and battles like nobody's business. I also liked A History of Warfare and Fields of Battle: The Wars for North America which is an interesting look at how geography shaped American history.

He compares the soldiers' experience at the Somme with Agincourt and Waterloo. Very good reading.

He was very good at showing the impact of change on military doctrine.

the podcasts from The Pritzker Military Library in Chicago? I know I have listened to many of them while commuting and doing the mindless part of my job on Sunday mornings. Pretty much all author visits and some cover WWI. I really have enjoyed them and the variety of topics and the Free part is really good to.

is "Germany's Aims in the First World War" by Fritz Fischer. Fischer was a German historian who took a great deal of heat when this came out in 1961. I haven't come across anything since that does a better job of spelling out how the whole disaster started.

Lyn MacDonald's Somme is also quite good.

The BBC (I think) did a series, The First World War, which was pretty good. They also did a much longer one, The Great War, which I've not seen, but was a model for The World at War.