Map visualization

I am designing maps and geographic visualizations. A user indicates a latitude and longitude somewhere on Earth and expects to see a map of that location. Tell me (in any combination of words, pictures, pseudocode or actual code) a method to tell the computer how to automatically decide on a zoom level for any given location on a map that will be interesting for the user. For instance, if the user indicates a location that is in the ocean, then the resulting map should not just be all blue.