Information I pulled from crf-usa.org (paraphrased):

He's in a class by himself:

"In many ways President George Washington must be put into a class by himself. Unlike the other founding fathers, Washington was a true non-partisan. He hated it when people divided into hostile groups, and he tried to avoid taking sides during political disputes. As president of the Constitutional Convention in 1787, he contributed almost nothing to the heated debates that took place. Instead, he used his considerable prestige to calm people down and get them back to their main job: creating a new form of government for the United States.

For his part, Washington reluctantly accepted the presidency. Jefferson told him: "We cannot, Sir, do without you." None of the other founding fathers, despite all their brilliance, could command the respect and trust George Washington did. Washington became the first and only president to be unanimously elected.

(Washington appears to have been one of those rare individuals in world history who fit the needs of his time. What made Washington a great leader was his understanding of what had to be done.)"

One important action of his was stepping down after two terms. Doing so was seen as a reinforcement of the idea that the new nation would not have a monarchy. This established the tradition of the presidential term limits, and was a strong enough taboo to keep all but three presidents from seeking a third term. The three were Ulysses S. Grant, Theodore Roosevelt, and Franklin Roosevelt; obviously only FDR was successful (Grant's and Teddy's attempts were for non-consecutive third terms). After FDR, the two-term limit was seen as important enough to become the 22nd Amendment.