It seems what you're really saying is you celebrate Columbus Day because it's traditional in your family.  We can rationalize anyone's actions, even our own.  And if those actions are 500 years in the past it's even easier to make what we want to of them.  Most Americans celebrate Columbus Day because it was their first introduction to the concept of history.  Not because it was important, but because it was the first day on the academic calendar that their elementary school teachers told them a 'true' story and then let them cut ships out of construction paper.  Since 9/11 comes earlier than Columbus Day the first stories told now are both fresher and darker.  Perhaps that's why we're being asked to take a new look at the old stories.  It's fine to celebrate your heritage.  Even if the virtues you want to admire weren't real there's merit in admiring the desire to explore and discover.  But ignoring the vices that accompanied those virtues isn't fine; admiring them is even worse.