There are many people in the U.S. State Department who have responsibilities connected to the UNESCO. As UNESCO further decentralizes, it seems likely that U.S. embassies in many countries will have increasing UNESCO responsibilities. Below I have linked to biographies of key policy level officials of the State Department who might have UNESCO interests.
John Bolton is of course in the news as the U.S. Ambassador designate to the United Nations. Bolton's biography on the State Department Website. Bolton’s Resume from the American Enterprise Institute.
Louise V. Oliver, Permanent Representative of the United States to the United Nations Educational, Scientific and Cultural Organization
Kim Holmes, Assistant Secretary, Bureau of International Organization Affairs (Which has oversight of relations with U.N. agencies, including UNESCO.)
R. Nicholas Burns; Under Secretary, Political Affairs (With oversight over State/IO as well as other Bureaus.)
Patricia de Stacy Harrison, Acting Under Secretary for Public Diplomacy and Public Affairs. (Karen P. Hughes has been nominated for this post, but not yet confirmed.)
and Assistant Secretary of State for Educational and Cultural Affairs. (Dina Powell has been nominated for this post, but not yet confirmed. Powell's White House biography.)
John F. Turner, Assistant Secretary, Bureau of Oceans and International Environmental and Scientific Affairs
Paula J. Dobriansky, Under Secretary, Global Affairs (With oversight of State/OES and several other bureaus.)
George H. Atkinson, Special Adviser, Science and Technology. (The Science Advisor to the State Department.)