I always find myself mesmerized by the air traffic exhibit at the air and space museum. It has planes, color coded by airline, flying across a radar map.
They use various days as samples–including September 11, 2001. (It is really eerie to watch air traffic suddenly stop).
There’s an app out now that creates visualizations of the day’s air traffic. You can also edit how you want to see the visualization, changing it according to your preferences.
Here’s my glitter-based visualization of air traffic right now. (Note, glitter in flight not recommended!)