After turning to Google Earth, I wasn’t pleased with the results, so I came back to Leaflet, worked a bit harder to figure it out, and found a great implementation to inspire me. My in process example is here – birthplace mapper. What this example does is to cluster the birthplace markers based their geographic proximity, separating and re-clustering them as you drill up or down.
This is really early in the process, as I plan to add more information to the markers, as well as fixing the ones that don’t currently display – mostly from outside the US, where state information may be absent. Still, the potential for this is high, and makes for a much better navigational experience than the Google Earth version I was working on. Try it out!