actually, late Jan is a good time. It's actually considered low season. The later in Jan you get the more crowded it is. Stay away from MLK weekend, it's close to the busiest of the year.
BSB is rarely crowded. Chair 5 (the old lift on the back side) gets pretty crowded, but the China Bowl lift isn't too bad.
One trick on really crowded days is to ski the lower half of the mountain. Hardly a line. (For example, Chair 8 at Lionshead.)
Good chance I'll be there then.