Create your own wifi with a cheap wifi router. Just plug it into the wall (don't connect it's Internet jack). The DHCP server is usually turned on by default, so your Apple TV, iPad, and iPod/iPhone should now show you the new network under "available wifi networks". Select it and you should be connected. You won't have internet, but you don't need it just to connect devices to each other.
Here's a $30 router that will probably work:
http://www.amazon.com/dp/B004N6259G/ref=asc_df_B004N6259G1868344?smid=ATVPDKIKX0 DER&tag=hyprod-20&linkCode=asn&creative=395093&creativeASIN=B004N6259G
The above is a simple/quick way to create a wifi network, but you should probably also add wifi security to the router and you might have to change the subnet to something out of the ordinary so that it doesn't interfere with an existing network.
We have an Apple TV connected to our projector. Our iPads flawlessly connect to the Apple TV, then we can use iPhones to remotely control the iPad. Since the iPad is no longer tethered to a VGA dongle, you could also just hold your iPad. We also have a Linksys wifi router that we take when we go outside of our office so that the above devices all automatically connect to it since it's already been added to the device wifi connections.
In my oinion, wifi for this setting is better than Bluetooth because of the range. You probably won't drop the connection with wifi by walking to far out into your audience while presenting.
Note: You should add a password to your Apple TV so that audience members with an iPad cannot take over your presentation. Of course this wouldn't be an issue if you add security to your wifi connection, which I highly recomend.
Hope that helps,
Dave
