I suspect the Democrats will have a few gains in the Virginia House of Delegates, but they won't come close to taking control of the chamber. Republicans
may net a seat or two in one of the New Jersey chambers, but there are far fewer districts there than in Virginia (40 vs. 100), and fewer than ten of those forty districts could really be considered competitive. Christie would have to have really incredible coattails for the GOP to make real gains.
I hadn't thought about the repercussions for the Virginia State Senate if Northam and Herring both win.
Now I almost don't want Herring to win. After the 2009 election they had the special election to fill Cuccinelli's seat in mid-January. I'm assuming a similar timeline would take place for Herring and Northam's vacancies. Article:
http://articles.washingtonpost.com/2010-01-13/news/36840852_1_absentee-voters-virginia-democrats-virginia-senate