This is an incredibly helpful thread, thanks!
I'm looking into doing this route in early July, but have a couple of questions:
1) Currently the only nonstop service on this route seems to be the 16:03 departure from Vienna, arriving Zagreb 22:43. A key reason for taking this route is to enjoy the scenery, so I don't want to be missing out on any of the good bits because it's dark. I see sunset at that time of year is around 20:50, so presumably there will be twilight until close to 22:00, so it's probably only Sevnica to Zagreb where the light will really be failing. Is this a particularly scenic stretch, or should I just not worry about it?
2) If we decided to stop somewhere along the way for a few hours, perhaps for a bit of an alpine hike and/or to explore a nice town, where would anyone recommend?
Thanks for any suggestions!