I'm planning a conference and am wondering if there are any typical trends about the cheapest days of the week to fly. I know the middle of the week is usually better, but what about Friday and Saturday? Which of these are cheaper? Any strategies to consider as an event planner if I'm trying to provide attendees with a good hub city for an event?

My home airport is Chicago ORD. Any good airports in California with consistently lower nationwide fares?  Thanks!

 
  There are generally more sale fares available for mid-week travel, but one of the key things to remember about mid-week travel vs. weekend travel is that even if a cheap sale fare applies to all seven days of the week, there will usually be much more availability for less popular travel days.  Not only will there be more seats sold for those days, but those seats will not sell-out as quickly. 

Which Days of the Week?
So what might these less popular days be?  Well, Tuesday and Wednesday are almost always a good bet for sale fares and more availability.  And although you may not have guessed it, Saturday is not a hugely popular day to travel either, as most folks like to get their weekend travel started on Friday, a very popular day (as are late-Sunday and early-Monday, which are both coveted travel days for those who are trying not to disrupt their work schedules.)

Picking A Cheaper Airport
Instead of thinking in terms of targeting a single airport with cheap fares for your attendees, what you might want to do is think of locations that can be served by multiple airports.  In California, for example, if you picked a facility such as the Laguna Cliffs Marriott Resort in Dana Point, your attendees would have a wider array of fares to choose from because they could easily fly into LAX, Long Beach International, John Wayne/Orange County Airport, etc. Besides giving them more choices, they would be flying into an airfare market that has a lot more competition and consequently more sale fares.  (Folks on a budget who are planning family vacations should also think about hitting airport dense areas for the very same reason.)