Did you know you can grade the discussion board directly through control panel? Also if you need to have separate discussions for individuals or groups you can manage access to the various forums so that one student may perhaps keep a journal that only the instructor and student can view or perhaps small groups can be created to view and comment on specific posts, just another way for students to interact!
Check out the OET’s BB course for some sample discussion board icebreaker questions.
Perhaps you could change settings after all students have posted, it might be a bit too much extra steps but is something we can explore.
Is this something that might be applicable to what I’m trying to accomplish in my ethics course, i.e. allowing all students to view the postings, but having grades/comments private?