http://en.wikipedia.org/wiki/World%2...senger_traffic
List of the world's 30 busiest airports (by passenger traffic).
Las Vegas does make it onto the list (#9), but serves a little over half the traffic that Atlanta does (#1 with a comfortable 9,000 passenger lead). It appears Vegas is barely bigger than Denver or Phoenix.
With Chicago, LA, and Dallas servicing so many flights, they may be options if a close venue could be found.