I find it disappointing that given TNG's emphasis on diplomacy, the only diplomats names that appear were either wartime figures or in-universe. None of them were internationalists/federalists. To that end:
USS George Marshall
USS Dag Hammarskjöld
USS Robert Shuman
USS Konrad Adenauer
er, George Marshall was a wartime figure. He was chief of staff of the US Army during WWII.
Adenauer is a good pick.