President Mohammadu Buhari is reportedly the first Nigerian President to be hosted at the Blair House. The official Blair House Guest List shows he belongs in a prestigious group including Nelson Mandela, Queen Elizabeth and Prince Phillip, Vladimir Putin and the likes. Read up on the Blair House Guest Book.
PS: There are reports Prime Minister Tafawa Balewa stayed there when he visited in July of 1961. See this video Prime Minister Tafawa Balewa Visits U.S. July 1961. There are also reports former President Obasanjo stayed there.