depending on how long you plan to travel, where in japan you are going and on what trains, sometimes it is better to get the suica/nex combo and save the pass to validate when you plan to take on train routes - http://www.jreast.co.jp/e/suica-nex/

that said, OP should look into using some miles on flights in japan less than 650miles also. they seem to be good value in the new program (did i just say that)...except you can only book two months out.