There are multiple solutions for showing/hiding, styling, and controlling the location of the "Read More" link for node teasers, including the excellent Read More Link module. In my case I was looking for a light weight, limited solution that allows the content author to suppress the display of a read more link for short articles, without any additional functionality.
The solution? Simply adding a new Boolean field to the chosen content type(s), adding a node display class to the site theme's template.php, and then updating the site CSS after determining the class that the theme assigns to a read more link.