The artwork looks better by itself, as well, some of your guests will like to have the freedom to frame only the portrait. Still, if it is important for your business/event, you can have your logo or other symbols at the bottom of the front page, but it is preferable to keep it as simple as possible. I'll be happy to add stickers (preferable - you can choose the quality of printing etc.) provided by you at the bottom of every front page.
Alternatively, you can have your logo printed, black & white (it works only for black and white with no shades), for free, for a limited number of sheets, 10 per every hour of the event. The backside of the sheet contains info for your guests to can learn more about the artist and story behind the art - "why I draw - find out about my artistic philosophy". The understanding of why and how the artist chose to express himself thru his work, makes the art experience more complete.