Hi Heather. My experience is that the ID should dictate most fo the creative effort since he orshe might understand the concept better than a graphic designer or developer. Creativity must aid learning and not just look pleasing. I am used to do everything because I like to have control over the entire process. As for the SME document, I like to use PowerPoint and use the notes as the script. This allows the SMEs to have a better view of how the final product will look. In Addtion, by using PowerPoint, you can add the audio script and graphics at the same time. When the storyboard is signed off, then you just import to Storyline and all you need to do is add animation, synch the audio and start the QA process. Some people called this method "rapid development". I have some samples that I can share.
In the past, I have see designers used Excel or Word to create storyboards. These two methods they are more prone to make mistakes and by more restrictive on creativity and ease of development.