Jim provided numerous examples of leadership which also answers my question of whether or not it's rare or common: apparently it's common. I need to think about why I was unable to come up with the examples myself and how this new insight affects my philosophical outlook. The Yeltsin and Mandela ones I might have gotten, but for our Presidents, here is how I've associated them with events up till now:
Kennedy - Cuban Missile Crisis
Johnson - Vietnam
Nixon - Watergate
Carter - Stagflation and Iranian hostage crisis
Reagan - OK, well, "Mr. Gorbachev, tear down this wall" is probably my first association, but at the time I thought Reagan was an idiot and a lunatic (sort of how many people view Bush now).
Clinton - One of two presidents ever to be impeached.
So, anyway, I'll have to think about why I've focused on the bad instead of the good.