Working Smart's got a long post with practical advice on how to position projects to one's boss. One snippet (also true for consultants):
"Most top managers have two basic needs: they want to grow their company and they want to increase their profitability. Whether they are a private company or a public one, this is the ticket to their personal success. If your proposal promises to do either, you've got their ear. If not, you're likely dead before you start."
(Via Fast Company)