I really liked this data visualization that I found here. It is a visualization of the timings when people leave their homes for work.
Since the data is available at a County level, you can get a better story and the trends are better understandable. The visualization is interactive and you can change the timings from the buttons. I like the play button which loops through all the timings and you don't need to click the buttons. If you hover over a county, it displays a tiny bar chart for it. I like this feature as it allows to understand the story for a county really well.
The visualization is made in D3.js and a lot of the code looks familiar to what we have done in class.