either way will achieve the same result.
I personally prefer to convert the template to a theme, then apply the theme to each of the pages
Yes, it is a little more work than being able to select the template in the wizard. But the reasons for making the change are discussed in post 2 of the thread CraigR linked to initially:
showpost.php?p=126128&postcount=2
also using themes can offer added functionality. If you where to use dynamic themes for example, you could allow you admins to select from a list a themes and use the one that they like best.