Small WiFi Network In a Noisy Environment

Use 5GHz A/N if your devices support it. I don't believe current gen iPads do, but some PC/Mac wifi chipsets do.

Get some hardware like a Wi-Spy Channelizer that will tell you what channels are most congested in your area and run your AP on a different one.

If you want to be a good neighbor, you'll keep your transmit power low. If you don't care about the booth next to you, crank that sucker way up.

Definitely use WPA2 with a long key so that people can't hop onto your wifi and contribute to the problem.

We don't do specific brand recommendations here, but get an enterprise product from an enterprise vendor. They typically have the most configuration options available for dealing with situations like this. If you spend $50 and get a Linksys from Best Buy, you're going to have a bad time.

If all else fails, you can build a giant Faraday cage and demo inside of that ;-)