One other option is SuSE. Novell is pushing the idea of free downloads of the desktop edition (live CD and install), along with a manual. http://www.novell.com/training/linux/register.html

It would carry the advantage of a big, familiar name, which might be of interest to IT professionals more than to hobbyists. Hoobyists will make one download and play with it, but IT professionals could conceivably spec linux for an entire enterprise migration. And the bigger the name, the more comfortable they might be in risking their careers on such a move.

Say what you want about the relative merits (I love Knoppix), but Novell has the name, and it also has certification programs to enhance the resumes of those IT Pros who spec it.

jd