The first time was in 2009: I traveled out to Titusville for the express purpose of seeing the launch. It was scrubbed twice, and then launched on the third try. Seeing a video of a rocket (or Shuttle) launch is very different from actually being there—even from 3 miles away, it's a visceral experience. Like live music. I wrote a bit about it back in 2014.
The second time was a year later, from 60 miles away in Orlando. I hadn't known it was happening. I was on a walk with my girlfriend, just wandering around in her neighbourhood in the dark, when we saw the sky go orange off to the east. Our befuddlement turned to awe as the tiny candle of the Space Shuttle rose over the houses and the treetops and disappeared into the clouds.