We've gone twice during Jersey week. It's packed. I guess that term is relative to what you're used to. We try to go during non-peak times during the school year and we keep experimenting. If you normally go during Christmas, Easter or summer then it won't seem so bad. Most people go from Sat. to Sun. so that Monday the parks empty out. Our kids don't get additional days off that week and only get off Election Day if it's a Presidential Election.
Here is a description from mousesavers.com:
"Jersey Week" - Usually the first or second week of November. The New Jersey schools have a teachers' convention (upcoming convention dates: November 9-11, 2006; November 8-10, 2007; November 6-8, 2008). Lots of people pull their kids out of school for the whole week and add on the weekend before and/or after, taking this opportunity to go to Disney World in the "off season." New Jersey is the single biggest market for Walt Disney World -- you do the math!