17 days in Japan?

Hi, It's my first time to japan, and I will like some recommendation to planning my itinerary for the trip in early Oct to mid Oct.
day1 - Osaka airport
planning 4-5 days in Kyoto, osaka, kobe, nara
4-5 days in Tokyo, I would like to squeeze in 3-4 days in Hokkaido.
Is it possible to take Night train to reach from Kyoto to Hokkaido/Hakodate? Or do you suggust I just see most of Kyoto and tokyo only? would it be a waste of travelling time to head up north? I just want to see most of everything in Japan in the 17 days. Please advise. Thanks.

B2,17 days will not cover "everything" by a long shot. I would suggest that you concentrate on the area from Osaka to Kyushu and back to Tokyo. Are you flying out of Kansai or Narita ? 17 days is probably a nice time frame for Osaka-Kyoto-Himeji-Hiroshima-some Kyushu and Tokyo/Hakone fits at one end depending on your flights. There is a night train from Osaka to Sapporo ( about 22 hours ) but it is a long way to go unless you have a special interest up there. There is so much to see and do in the south I would suggest holding off on Hokkaido for another time.

Hokkaido and Kyushu both deserve a trip of their own. There are interesting places to go in Honshu alone that can take more than 17 days for a first-time visit. So to cut down on long train journeys, concentrate on Honshu. I can assure you, after your first time visit to Japan, you will want to go back and back, and back again.

For a start, take a look at the following, though it does include Nagasaki in Kyushu:
http://www.japan-guide.com/e/e623.html