A couple of weeks ago while I was driving around northeast Nebraska, I entertained myself by considering recent presidents and their major accomplishments and failures. Yeah, I do stuff like that for fun. Here are the conclusions I drew.
Reagan's greatest accomplishment was putting in place the policies that precipitated the elevation of Mikhail Gorbachev in the Soviet Union and ultimately helped to lead to the end of the Eastern Bloc. Also noteworthy were his disarmament deals, as Reagan did believe in a nuclear weapons free world (Thatcher thought Reagan was naive on this point).
Reagan's greatest failure was the massive growth of the debt during his presidency, when he had in fact run as someone who would reign in the deficit.
George H. W. Bush
Bush greatest accomplishment was his successful navigation of the collapse of the Soviet Union and the Eastern Bloc, the end of the Cold War, the reunification of Germany, and the empowerment of the United Nations in dealing with Iraq's invasion of Kuwait.
He failed to predict how his involvement in the Middle East would precipitate al Qaeda. Also, I believe the L. A. Riots revealed a lack of addressing urban poverty and racial injustice by his and the previous administration.
I think his biggest accomplishment was the bailout of Mexico and overall how his economic team handled a series of global economic crises in the late 90's.
His biggest failure was either 1) Not reforming entitlements, despite running both times on that idea and then never offering a reform plan (he squandered an opportunity for real reform) or 2) Policies that ultimately led to the housing and financial market collapses of 2007-8 (though others contributed to that as well).
George W. Bush
His biggest accomplishment was his initiative to address HIV/AIDS and malaria in Africa. Either that or his agreement with India which may pay off in the long term.
His biggest failure, I believe, was the opportunity that he squandered. After 9/11/2001 there was unparalleled national and global unity which a great president could have muster in order to achieve great things (such as steps toward the Millennium Development Goals). Instead, he made horribly bad decisions that squandered unity and goodwill, utterly divided the nation, and generated further violence globally. Probably the greatest missed opportunity in American history.
I believe his greatest accomplishment will have been broadening the core American narrative. He has done this by being himself but also in his rhetoric (the examples he uses, the stories he tells, the names he mentions--did previous presidents talk about Fanny Lou Hamer?) and in the cultural choices he and Michelle have promoted. We helped to create a model for America's more pluralistic, multicultural future.
And his greatest failure was not recognizing that when he had control of Congress with a filibuster-proof Senate that he should have achieved as much of his agenda as he could. He frittered away almost a year futilely trying to negotiate on health care.