There is great riding in Hunterdon, Warren and Somerset Counties. I usually ride out of L'Ville and Bull's Island (on Rte. 29 north of Stockton, NJ) several times a year. The terrain and scenery is quite different than S. Jersey.
If you do any touring, Bull's Island is a great destination. Weather permitting, the GF and I will be riding to Bull's Island on Good Friday for a long weekend as we have done the last two years. The first year we had the place to ourselves Saturday night before Easter. Kind of spooky. Last year, there were only a handful of people there.