While there is not one answer to this question, here are a few things to consider when deciding where to place the Graphic Recorder:

• Inform the speaker well in advance there will be a Graphic Recorder there to support their presentation.
• If you place the GR at the back of the room, it can be distracting for the speaker to watch turning heads in the audience.
• To maximize the value of the GR, allowing the audience to watch the art unfold is a critical part of the process.
• A well lit area is important. Highly produced events may using a lot of moving lights, black lights (which cause color shifts), and pulsating lights. Be sure your AV crew is aware the GR will need clip on lights or portable lights for their work area, and quality sound.
• Consider proximity to loudspeakers, and in general provide the GR with a location that has strong acoustics. If the GR is on-stage, an audio monitor may be a necessity. 
• Placing the GR in a location that is easily visible to the majority of the audience allows everyone to access this additional modality of understanding and absorbing the information being conveyed by the speaker.
• If the venue is light-filled, consider the movement of the sun throughout the day and where it might be problematic.
• Consult with your GR before the event. A few camera phone shots of the venue can be very helpful to launch a discussion of the options for placement of the GR.

Apologies for the poor video quality. The video is a timelapse of a full day event with faculty from an elementary school. As part of their team building day, we created a 10 year timeline (Journey Map, or Heritage Wall) of their school. The educators worked in teams briefly in the morning to review their institutional history and post stickies, which I categorized with their input. After a review of the finer details with workshop leaders, the drawing began. The staff moved to other activities for the day, and we came together to wrap up the day with a review and appreciation of their Heritage Wall. This type of activity reinforces milestones and serves as a powerful on-boarding activity for newer staff.  The artwork is now hung in the school to celebrate their upcoming anniversary.