I find there are less wild and load people and many wait for the wkend. This July we are going to try out a new KOA for Wed, Thur, Fri. It is just above Santa Paula california. Which is above LA. It is close to home and may be the place to get away to if we want a hot shower. But there are many NP that are near too.
http://koa.com/campgrounds/ventura-ranch/
and week days have more openings too.
Weekends are fun for Gatherings but most include Thru and Fri for those folk who have wkends off.
I work in retail so weekends are out unless I ask off way before.
But week days the boss says ok to.
Weekends also are more likely to have a big event making unplanned camping a little harder.