I've been to some of the ghost towns in the state. However, December may not be the opportune time to get to many of them. Most were located in mining districts and the mines were primarily located in the mountains. I've gotten stuck out there in December because of snow. Be careful if you go, take supplies if you get stuck out, and let someone know where you are going.
Many of the ghost towns are true ghosts, with little left but a few rocks indicating where building foundations had been. Others, like Eureka, never were real ghosts, but still had many empty buildings. With the new gold mine north of town, everything is "booming" again. Belmont is a good one to visit this time of year. Manhattan another. Both are lower elevations with decent roads as there are still residents there. But even places like Caliente have interesting things to see. I'd stay to the south, although there are lots of ghost towns around Ely.
There are a few ghost towns/sites that were associated with the Pony Express Trail, the stagecoach roads, and the railroads (check out Palisade near Carlin). While they may be lower in elevation, they're also often on dirt roads that get tough to traverse when they get wet. Take chains to be safe.
A few of my links:
http://www.cmdrmark.com/ghosttowns.htmlhttp://www.nevadadventures.com/index.htmlhttp://www.ghosttowns.com/states/nv/nv.htmlhttp://silverstateghosttowns.com/ghosttowns.htmlhttp://en.wikipedia.org/wiki/List_of_ghost_towns_in_Nevada