K-12 CMS

Hello everyone,
This is my first post to the list, so I apologize if this is an often
asked question, or if I am missing pertinent information.

I work for a medium sized K-12 school district in Michigan.  We are
looking for a CMS to replace our very limited home-grown CMS.  The
primary need/use for a CMS at our organization is to provide Teachers
and staff with the ability to simply and quickly post information to our
website.  They need the ability to post information for "external use"
(parents and students from home) and "internal use" (only accessible by
staff/teachers, and not by the general public).  Our current home-grown
system allows our staff to post content to our external website, but
provides them with no method of customizing the look/feel of the data...
as in they have no way to set the layout of the data... and are unable
to make changes like: color, fonts, alignment, size, etc. etc.

We currently have one district level Programmer, who would be
responsible for the primary HTML coding/customization and framework
design of the CMS.  We also have a central "Web Master" who is
responsible not for actual content, but is there to provide end user
support and answer questions.  We then have our Teachers and Staff who
are responsible for the actual content.
Obviously, Open Source solutions are desired, since there is no
direct/initial purchase price associated with them.  However, we are
fully open to commercial solutions as well.

The features that we need foremost are:

1.  Ease of Use.  This is by far the biggest consideration.  The
Teachers/Staff need simple ways to post customizable content without
knowing HTML... Drag & Drop interfaces are great.  The editor need not
be within a web browser... however, 99% of our workstations are Apple
Macintosh computers running Mac OS X (10.3).
2.  Discussion forums.  The ability for Teachers to create discussion
forums/topics to interact and communicate with students.
3.  Online Calendars.  Many staff/teachers in the district want the
ability to add and maintain calendars for public access within "their
own" portion of the website.
4.  Online Tests/Quizzes.  The ability for teachers to be able to
quickly and easily create simple tests and quizzes online would be a
great feature.
5.  Surveys.  We often have need to survey parents and students, as
well as our own internal staff.  A system that would allow Staff to
simply generate surveys would be very well received.

Can anyone provide me the names of some CMS's that would provide these
features?  I have looked at www.cmsmatrix.org, and I have a list of
potentials, but I would really like to hear from people who have first
hand experience.

Thank you,

Jonathan Sherman
Network Manager
Hudsonville Public Schools