I have to agree with what was put in the PassPorter. The parks are the most crowded around holidays and when kids are out of school, so if you won't to avoid a big crowds stay away during those times. (Exception) Probably the least crowded holiday at DL is Halloween. You don't have to deal the families that come there from other states or countries during that time.
Have fun planning your DL trip!
"Here's a little pixie dust to make your DL vacation magical!"