I'm going to Beijing in June and want to visit the Great Wall. I would like to take train, bus or something from Beijing to a nice spot at the wall and walk for a whole day, and then get back preferably by train or bus at the evening. I'm young and healthy and can walk long distances. I would like to walk on a part of the wall that isn't full with tourist, but a place where I could find a restaurant for lunch/dinner during the day not to far away from the wall. Any suggestions?