It's hard to answer your question w/out offending someone,
I'll give it a shot since I don't care as much about offending someone
I try to avoid, as much as possible, South Sac, West Sac, Rancho, N. Highlands, S. Natomas, Del Paso Heights and Rio Linda. Most places are okay during the day, but those are the areas I don't go through at night, mostly because I have no reason to.