It would be great with a checkbox on page level, where it is possible to disable SEF url and by that, the page will have the "original" default.aspx?id=XXX url instead.
One of our costumers has experienced problems when linking to the sef url from their newsletter system and they also uses some pages in an app that conflicts with the sef urls.
I know they can just find the page id and link to the url manually, but they are not that technical :)