Last week of March tends to be a busy spring break time. Expect a number of schools to be out that week. Other than our local school district here in northern California and most of the University of California system, I don't know which ones. There is a good southern California resident ticket offer with no blackout dates though, so if any local schools are out, Disney will be an attractive destination. My recollection of March is also that we usually see a lot of youth involved in music programs, beauty pageants, cheer competitions, etc. touring the parks in groups. The food and wine festival at DCA will also be in full swing and draw crowds.