This is all completely extraordinary.  A conference on democracy and security in Prague, featuring some of the world's most famous political dissidents, was locked down by American security personnel after a speech by the leader of the free world.

I know that Americans typically aren't terribly hot on irony, but surely contrariness on this scale must have struck somebody as a little odd.

The lessons for mere mortal event organisers are simple:

"[T]he acoustics were abominable. Only those lucky enough to sit in VIP rows at the front could hear the insights from the podium. The organisers had failed to realise that the best bit of a conference of this kind is the hobnobbing during the coffee breaks, not sitting quietly while listening to people read prepared statements. The panels were too big, the speeches too long, the timekeeping poor."

and

"There was nothing to eat or drink; no access even to lavatories. If the Czech hosts and their Israeli partners had offered champagne and canapés, nobody would have wanted to leave—the company was excellent."

In other words, treat people with respect.  Don't think that you (or any of your speakers) are going to have anything groundbreaking to say.  Leave plenty of time for people to discuss what has been said without getting too involved yourself.