The Great Nothing is a traditional out and back twice around the room plan that has been around since the early days of model railroading. Since the pike is based on GN's Coast Line between Seattle and Vancouver, Seacouver serves as both terminals, allowing in effect point to point operation. Trains leaving through the right leg of the wye are southbound from Vancouver and arrive back over the left leg which represents Seattle. The third leg of the wye is used for continous running or to turn trains in the terminal before heading back over the line. However,it is anticipated that most of the time both passenger and freight trains will be broken down.
I would have prefered much longer sidings, but compromise is necessary to have anything workable. The staging tracks are much longer having a capacity of 22-25 cars, which is too long for any of the siding or the terminal. Those trains will arrive and depart from staging and just drop/pick-up cars at each town. The longer trains will provide a reason for the heavier power used between Everett and Seattle. The main line should be approximately 180' which will provide a decent run.
Much more information on operating the layout can me found on the Model Railroad page