Richard Falk, recently retired as the United Nations Special Rapporteur for the mess in Israel-Palestine (latter not part of his title!), has written a summing up of recent efforts. Will not fit with everyone's views, but worth a read just to inform ourselves. "Why the Peace Talks Failed--And Should Not be Resumed."
He is also retired from Princeton, University of California, etc. Was Professor of International Law. A Wikepedia Bio.