I used to run sound for bands and the guitarist never thought he was loud enough. In the same way, the photo booth can't be too close to the action. True, it should not be on stage, but follow these simple rules to consider placing your photo booth.
1. Place it close to the action. Guests want to be where 'it' is happening, which is usually near the dance floor or sight of the dinner tables. The worst thing to do is tuck it around the corner where it is not visible. It won't matter if the DJ announces it every 10 minutes, unless it is visible, it won't be used.
2. Interrupt the walkway. Don't Cause a fire hazard but put it in a place that people have to almost walk over to get around. That will help people see the booth and interrupt them to go have a little fun. If it is important to have, it is important to use. Keep it out of fire lanes, but put it in front of their faces.
3. Let it Breathe. The beauty of an open air photo booth is that everyone can see how much fun you are having. They also get cool ideas about what to do. The social/print kiosk is going to generate it's own line and entertainment so it needs its space as well. The photo booth can sneak into a 5x8' space, or it can entertain an entire group in a 20x20' space.
Turn the photo booth all the way up to 11 and have some fun!