Matthew Ericson, deputy graphics director at The New York Times, talks maps and when you should try something else:
Maps also a terrific way to let readers look up information about specific places. On election night, they answer questions like like "Which seats did the Republicans gain?" or "Who won all the seats in Oregon?" or "Who won my Congressional district?" You don’t have to remember the number of the House district you live in — you can just look at the map, zero in on the area that you’re interested in, and see if it’s shaded red or blue.
And obviously, when the story is completely based on the geography — "How far has the oil spill in the Gulf spread?" — there’s nothing more effective than a map showing just that.
But sometimes the reflexive impulse to map the data can make you forget that showing the data in another form might answer other — and sometimes more important — questions.
The full post is worth a read, chock-full of examples.