What is the best way to have the back cut?

I am getting my hair cut today and I really need quick advice. Right now my hair is cut in a layered bob where the sides are just below the ears and the back is longer to about my collar. I am planning to get it all cut to the length of the sides (just below my ears) which will leave the hair down the back of my neck exposed. I don't know what to do with that. Should I get it shaved? If so how short and how far up? Should I get the back tapered, graduated, or something else. Please help me out soon. Thanks.