I learned through one of the Webinars here that the person within the company you should be querying with film scripts is the Creative Executive. I believe if you have a TV pilot rather than film script, you should query the Development Executive. If the company has neither listed, I would query the lowest ranking employee. If you're lucky, they'll have the words TV or film in their title.
If they only have a CEO and President, they're a small company, and you can probably query them directly. On the larger ones, though, I wouldn't contact anyone with a title like CEO, President, EVP, SVP. If their title makes them sound like they're on a board of directors, I won't query them as tempting as it is.
