Dear Rabbi Kornfeld,
As an addendum to the d'var torah regarding Eisav & Yishmael, I recall a drasha given by the mashgiach of the Providence beys medrash, Rav Yosef Lipson. I don't recall whom he quoted. He stated that the three-letter names used during hoshanos (ani and v'ho) were (as noted recently in sukkah) the first and 36th names generated from three 72-letter p'sukim. He mentioned that these names constituted a summary of the subsequent groups of 35 names, each of which were associated with the 35 nations of Yishmoel and the 35 nations of Eisav.
Thank you very much! (The Gaon of Vilna writes in the Tikunei Zohar, Tikun #13, that there are actually 72 -- and not just 70 -- nations, two of which are Esav and Yishmael which are the heads of all the others, as you said.)