I think the three weeks after Thanksgiving is a great time to go. Crowds are usually at their lowest for the year and the resorts and parks are decorated for Christmas. MVMCP, the Osbourne Lights, and the Candlelight Processional are also can't miss events. It can get a little cool though, especially in the evenings, so it's wise to bring jackets just in case.
I was just checking dates for the deluxes and moderates. It looks like summer value season at the deluxes start 7/20-10/1 and the mods 8/3-10/1. A small difference.