I am purchasing enough laminate flooring to do my entire upstairs. It includes bedrooms, closets, and an L-shaped hallway. I want to do this is the best possible way. I am especially interested in how to handle the hallway. Should I try to do the upstairs as if it was all one floor, i.e., having the panels all going in the same direction, thus avoiding any transitions at doorways, etc.? I have attached a diagram of our upstairs, Any tips will be greatly appreciated.

It is recommended to have an expansion gap every 20 feet of width across a laminate floor. A T-molding solves the problem so a couple of T-moldings at the side rooms' doorways would be good, if you run the flooring parallel to the step's hallway. You should get away with none at the other doorways, I would think. You may need a bull-nose reducer at the tile, if it is not the same elevation as the floor surface.