Internet Access
Internet Access is vital in the modern convention. Not only might it be used for science talks using offsite resources, or key to your hybrid convention, fans will be busy on their phones and tablets all day, both socially and checking your website/programme app. If your membership is local, they may be happy to use their mobiles, but check that signal reaches into the depths of the site. International attendees faced with high roaming charges will be keen to switch to wifi. Hotels and convention centres trying to charge extra will be unpopular, try to negotiate group access.
Fans will be heavy users, and may overload the network. Do you want to setup a separate staff network for internal and program porpoises. If you have abandoned wallyphones in favour of the internet, how would you cope if it struggled. Running 2 networks might appeal to techies, but could confuse everyone else.