What are some options for a 90 degree turn in a long hallway for laminate flooring?
It's really a matter of personal taste and the other aesthetic aspects of your home. There are basically 3 options, as I see it:


Keep the flooring oriented the same direction throughout. Obviously cross-hall boards may look odd depending on the style of the flooring. In a very short hallway run it may not be a concern.
Use a T molding to transition over a change in direction, orienting the seam perpendicular to the hallway. This is probably best done inline with the view from the living room, where it'll be less noticeable. 
Use a T molding at a 45 degree angle between the wall corners to essentially miter the entire hallway (like a picture frame). You'll see this more from the living room, but it gives more symmetry from the perspective of the hallway itself.


I don't think a herringbone turn is possible with most laminates due to the disparate tongue and groove shapes. That might look nice, though.

You'll need to decide which approach results in the least disturbance to the ambiance created by your new floor.