If you plan on bringing a computer to Defcon and/or Black Hat, think twice about plugging it into the conference network or connecting to the conference wireless networks.
If you do insist on bringing a machine to the conference floor, you had better take a pristine image without any form of even remotely sensitive data on it.
Do not communicate any authentication information at all, unless you are POSITIVE that it is protected.
If you rely on a VPN-like connection to tunnel your traffic, make sure that you authenticate BOTH SIDES of the tunnel.
Do not forget to turn off the WiFi and the Bluetooth settings on your mobile devices. Leave that iPad at home or in the room.
I am not too worried about using the hotel's network at Ceasar's, but don't even consider plugging it in if you stay in the Riv.