Mapping changes over time

A fellow courserian mapped the decline of Monarch butterflies and it had several elements:

1. An external data source (in this case: Flickr) with geocoding
1. Photos are geotagged
2. A time line
1. 2008 to 2013
3. Good visualization 
• a heat map was used
4. A basemap
• Imagery was used I believe

If I'm running a hospital network and I have information such as aggregate patient location, I would be interested in seeing where patients are coming from i.e.

1. An internal data source with geocoding
• patients are located say via postal code
2. A timeline
• last 5 years
3. Good visualization
• a choropleth, or graduated circles
• or a heat map
4. A basemap 
• Either imagery or split by postal code or natural subdistrict