Closest to my home is Summit Rd (~ 1 mi) in Mountainside, NJ, starting from Corrinne Terrace (get there from New Providence Rd. - avoids riding along Rte 22).

Next closest are Johnston Dr./Hill Hollow Rd. (~ 1 mi each) in Watchung, NJ.

Claremont Rd. from Bernardsville to Mendham (~ 2½ mi). This past Wednesday, I did Summit, Johnston, and Claremont all in the same ride, with descents down Hill Hollow and Summit on the way back.

In Hunterdon County, I miss riding up Stanton Rd. from Rte 523 and then making a right up Stanton Mountain Rd (~ 8-9 mi if you loop back around & up to the top of the reservoir). And just north of Rte 22 in Lebanon/Tewksbury, there are a network of roads that you could connect for some sweet climbing - Cokesbury Rd., Bissell, Deer Hill, Rockaway, Philhower, etc.

According to njbikemap, Summit Rd is the biggest climb in Union County & Claremont is the biggest in Somerset (as well as taking you to the highest point in the county). This summer I want to do both of these, as well as the biggest climbs in Morris & Hunterdon, too, all in the same ride.