I'm looking at going from Hiroshima to Sapporo with a JR pass (let's say flying is not an option). I know I have 3 main options:
1) Hiroshima to Osaka + Twilight Express to Sapporo (know I will pay a supplement)
2) Hiroshima to Tokyo + Cassiopeia or Hokutosei to Sapporo (know I will pay a supplement)
3) The whole way on 'regular' trains without sleeper berths

Questions:
- Which is the most scenic route, or does it really make a difference? (I know Twilight express is along the coast?)
- How far in advance do tickets for Twilight Express, Cassiopeia and Hokutosei book up (I would be looking for the cheapest sleeper)? I cannot book until I reach Japan and activate my JR pass (~2 weeks before I want to take the trip - will this be enough time?)
- Re: Twilight express, what days/times does it run? I want to take it in mid-June and likely on a Tuesday- is the schedule out yet? Where can I find it (Hyperdia doesn't seem to have it, and I can't find it on the English JR west site)
- Is trying to get there on a 'regular' train with no sleeper berths a huge hassle (let's say time is not an issue)? Looks like I can depart 7:15am from Hiroshima and make it there by 10:56, with 4 stopovers.

thanks!

According to the wiki page in Japanese (I can only the read Chinese characters), the southbound Twilight Express operate on Mon, Wed, Sat and Sun; northbound on Tue, Thur Sat and Sun. But daily during Golden week and between mid-June and mid-August. And yes, it goes along the northern coast of Honshu.

You can see the stations and times on the English wiki page.

http://en.wikipedia.org/wiki/Twilight_Express
http://ja.wikipedia.org/wiki/%E3%83%...83%AC%E3%82%B9

I would fly,lol. Since that is not an option I would probably opt for the shinkansen from Hiro to Sapporo during daylight. I have traveled from Odawara to Hakodate one day and that was a long train day. You might consider stopping in Hakodate and continue to Otaru in the morning and then back to Sapporo . Hakodate is a cool little town with great morning action at their fish market and a nice little hill to take in all the sights from.
There is the Kokusai Hotel a short walk from the JR station and right next to the morning market which you will pass by on you walk back to the train station. Very convenient and a nice place for one night.

The night trains will be passing the shoreline mostly in the dark. Here are the routes:
http://www.japan-guide.com/e/e2356.html

Aloha!

Thanks rkkwan! That is very helpful.

hawaiiantraveler- that is a good idea (hiroshima-hakodate, overnight, hakodate to otaru, day in otaru, otaru to sapporo) and something that I hadn't considered. This will give me some extra time in Hakodate (which I had wanted anyway). I will definitely keep this in mind.