Nixon to China and other ironies of presidential politics

This seems completely bizarre until you think about it for awhile, but...

Often, it's the "least likely" president who presides over reforms in important areas.

For example...

it took a Nixon to go to China

and

it took a Clinton (with a Republican Congress-- after the 1994 Democratic beat-down) to get amazing welfare reform.

If Obama has such a moment, what will it be? Here are two to consider:

-Social Security reform: privatization?
-education reform: vouchers funded at the federal level?

Given his willingness and ability to change positions-- and his desire to promote change and hope...

and

given some interesting racial angles (the negative rate-of-return for African-Americans from SS and our amazingly expensive and low-quality inner-city govt schools)...

these two huge issues are on the top of my list of hope and change. (I would strongly prefer that vouchers be financed at the state or local level, but would settle for federal education dollars being diverted into vouchers-- to shake up the monopoly power of government schools.)

Abortion fits all of the above, but I think that's way too far off the "hope" reservation.

Thoughts? Other candidates?