Configuring Drupal for different publishing roles can be very time consuming. There are lots of modules to install, settings to configure, permissions and roles to grant, input formats, content types, and the whole bandwagon, and these can be very difficult to setup again when you create a new website.
You have to duplicate your database, delete your content and start again, hoping that you don't forget stuff you need.
Content types and input formats are hell to setup, and when combined with WYSIWYG editors, taxonomy control, better formats etc, it gets pretty frustating to start all over again. I have a number of different Drupal installations all setup individually. I initially tried multisite but that references the module and theme installations and not the settings and configuratons.
I also considered multisite with some shared content tables, but came down in favour of Domain Access. My approach is to have a different editor for each site. All content for that site is published only to that domain, so if I want to move that domain into its own installation it becomes a matter of creating a copy of the database and deleting all content, users, roles, taxonomy etc that are not relevant to that domain, and moving it to the new installation.