I will be traveling all over Japan for 7 weeks. I am wondering if having a Green JR rail pass will make it easier to get a seat on some trains (e.g., if Ordinary seats frequently sell out on some routes). I normally travel coach class, so I would prefer not to spend more money than I need to.
Also, I plan to buy two 21-day passes, and will have thus have one week not covered by a rail pass. I plan to spend my first couple of days in Tokyo, then train to Sapporo. Should I wait until I depart for Sapporo before starting my rail pass? (I.e., will local travel around Tokyo, and from Narita Airport to the city, be low enough in cost that it's not worth starting the pass the day I arrive at the airport?