CSS: "display: auto;"?

The auto option that several CSS attributes give is really useful. However, there doesn't seem to be one for the display attribute. I would expect this to set the display attribute to the browser default depending on the tag; e.g., a <div> would reset to display: block;, but a <span> would reset to display: inline;.

1. Is there a display: auto equivalent I've missed?
2. If not, why not?
3. What's the most elegant workaround? (I'm working programmatically, specifically with jQuery.)