The question is how much comes off?  That depends on, not as much style as what you are looking for in society.

 

For instance, you might want the "clean cut" classic guy hair cut... which means the back and the sides are short.  Sometimes the back is a little long and the sides short, or the back is short and the sides are long.  Do you want to cover the ear or have it shown?

 

The top can be long.. long enough that when you comb it back, it ends somewhere behind the crown... or it can be shorter and combed over, side ways or what ever.

 

It depends on the face.  Guys faces should be square.  An illusion of a square jaw is good.  Have you ever seen a presedent with a limpy jaw?  Even George Wahington's jaw was painted to HIS satisfaction to give him that square jaw look.  Boyishness only goes so far and then it's gone and the square jaw it looked for.  Even beards are molded to give this.

 

Basically, looking at pictures of guys with cool haircuts and presenting them to a hairstylists can be risky... since they have to shape everything to it and it might be impossible to get.  Look for a picture that resembles your own face shape.  If it looks good, that's the one.  But, only a hairstylist trained to find this for you will be able to give it to you.  Just don't pick something from a model who does not have your face shape... yikes...