The very least important thing about 9/11 is how I, personally, spent that day. But you may find it interesting, and I can certainly vouch for it.
At about 8:30 in the morning, I was on the phone with a colleague, talking about the day ahead. We were both at home, in New York. We worked at National Review, and this was a “Production Tuesday”—the day on which we got large portions of the magazine out.