What else does your itinerary include? As much as I love trains, this is something you might want to consider getting a Japan Air Pass for. The price might just come out the same, but you save more time.

I must have a good memory or something because I still remember this post:
http://www.flyertalk.com/forum/japan...-railpass.html

Check out the photos:
http://hodo.travel.coocan.jp/s/burut...mg/hama_22.htm
Carpet car.

Akebono train (goron to shito seats)
http://hodo.travel.coocan.jp/s/burut...t/hakgt_04.htm

Night trains are a dying breed. I don't expect those trains to be around in a few years other then the more luxury (money making) night trains. If I ever get time and money, giving the Twilight Express a try would be great.