Hey everyone. I'm a software engineer at Meraki (mentioned earlier in the thread by dotwaffle) and wanted to chime in and offer what I can. Our gear is commonly used at conferences, including the most recent LeWeb, a conference in Paris with about 2,000 attendees and VERY heavy WiFi use (social media types that are tweeting, blogging, posting photos and accessing WiFi from their cell phones and laptops). We covered a 12,000 square foot room and other areas without any downtime or customer complaints. This was a huge improvement over the 2008 conference, when poor WiFi topped the list of attendee complaints.
Dotwaffle posted a link to our blog post about LeWeb which is worth re-linking. That photo was taken when the speaker asked everyone to hold up their iPhone.
We used MR14 access points with channel spreading and band steering enabled. This allowed us to use the entire wireless spectrum and avoid congestion on a single frequency (both of these are 1-click options when configuring your network). I'm happy to answer any technical questions you might have, or you can visit our website to learn more.