January is normally coldest month of year, a bit colder than February. But for some reason, to me January always feels better than December. Go figure. At any rate, you'll need to have cold weather gear. Above comparison to Chicago weather (but much drier) is apt.

Since you've already stayed in the Wangfujing area in the past, maybe try something else. Maybe try something in a livelier area, like the Opposite House Hotel at Sanlitun Village? The Westin Chaoyang, Kempinski, and Kunlun Hotels are also within short walk of Line 10 subway, and closer to places that are more night-life friendly. Or the area of the JW Marriott and the Ritz-Carlton.

Just remember that in a Beijing January, people aren't going to hang out on the streets, sidewalks, and rooftop bars at night like they would in September-October. Everything goes indoors.