On the occasion that a client doesn't need or want the full functionality of our Sitemanager, we recommend and setup Macromedia Contribute. This software's primary purpose is to allow contributors to add content to a website without needing to understand html or ftp.
The last post states that this software allows for the user to control everything within the body tag, which is not true. Using Dreamweaver, you can insert editable areas anywhere within the body. So you can create your tables that preserve formatting and insert editable areas where they are appropriate. In cases where the design is very static and sensative to minor deviations in length and size of content, you may want to insert an Iframe or a DIv with overflow:scroll in order to avoid formatting problems.
Contribute is very handy if you want to add text to an existing layout, however, if you are trying to manage a business website I would suggest
http://www.ibuilt.net or
http://www.dotnetnuke.com