This is one of the first subjects I studied when I began to question my previous eschatological beliefs. The best book on the subject that I have found is "Before Jerusalem Fell" by Kenneth Gentry. It deals with the internal and external evidence of both the early and late dates. What suprised me was the lack of evidence for the late date. In fact, the late date view seems to be soley dependent on one paragraph from the writings of Irenaeus.Even that is questionable as what he was reffering to. Don't know which Bibles and commentaries you referred to but many hold to the early dating.
Philip Schaff (1877)
"On two points I have changed my opinion -- the second Roman captivity of Paul (which I am disposed to admit in the interest of the Pastoral Epistles), and the date of the Apocalypse (which I now assign, with the majority of modern critics, to the year 68 or 69 instead of 95, as before)." (Vol. I, Preface to the Revised Edition, 1882 The History of the Christian Church, volume 1)
"The early date [of Revelation] is now accepted by perhaps the majority of scholars." (Encyclopedia 3:2036.)
"Tertullian’s legend of the Roman oil-martyrdom of John seems to point to Nero rather than to any other emperor, and was so understood by Jerome (Adv. Jovin. 1.26) (History 1:428.)