I'll be using a 2 week Japan Rail Pass in November. I've been to Japan before, spending time in Tokyo, Kyoto and Hiroshima. This time I want to go further afield and include Sapporo and Hokkaido.

A night train seems like a good option for me, both to save time and, if the free seat option is good, money. I've looked at the list of night trains at: http://www.japan-guide.com/e/e2356.html and see that some of the night trains have a no cost seat option for Japan Rail pass holders. Has anyone tried any of these "free" options? The "Goron to Shito" from Tokyo to Aomori and the "nobinobi carpet car" on to Sapporo would be the ones I'd most likely use.