Looking for good example KML to ship with Cesium

We’re putting the finishing touches on Cesium 1.7 (the first to include basic KML support) but I’m struggling to find some good (and free to redistribute) sources of KML data.

For the Sandbox example, I thought it would be good to have the following:

  1. A basic KML (placemarks with balloons, maybe some basic polygons or images).

  2. A KMZ with embedded images and data (maybe something with lots of geometry).

  3. An animated KML (or KMZ) that makes good use of TimeSpan.

  4. An animated KML (or KMZ) that uses Google’s gx:Track extensions.

  5. A KML with a basic NetworkLink that points to something more interesting.

The only limitation is size, since these will ship with Cesium I need to keep them small. I think I have a few of these covered, but I’m hoping the Cesium community can pitch in with some links and ideas.