aggiegirl

For the times I am wanting for my Ljubljana-Salzburg train journey and Vienna-Prague journey, I will have to make a change at Villach and Breclav respectively. Will these trains be crowded and will I have any trouble finding space for my luggage? Thanks in advance!

Catbert

I took the train from Villach to Ljubljana in June and it was one of the most crowded trains I've ever been on. There were lots of passengers riding in the hallway.

Intrepid1

If you are at all concerned, get seat reservations (assuming these trains are reservable) once you arrive in Europe (cheaper than getting them elsewhere).

PalQ

And since train travel in Eastern Europe is still so cheap go first class if worried about crowding - certainly will be less mobbed than second class could be.
You should research schedules again as my Thomas Cooks lists three daily trains that do direct between Salzburg and Ljubljana - no changing in Villach - since they start in Munich or Salzburg you should have a seat (reserve one) before the train gets mobbed in Slovenia apparently. One train IC211 leaves Salzburg about 9am.
Likewise there are several direct trains Vienna-Prague - no changing needed.

aggiegirl

PalQ: I'm going from Ljubljana to Salzburg, not the other way around. The only two options I see with no change during regular daytime hours would have me arriving in Salzburg at 2:55 pm (14:55) or 4:48 pm (16:48). If I take the 8:05 am, with one change at Villach, I can get into Salzburg by 12:55, giving me a couple of extra hours in Salzburg. The date of this train trip will be April 2. Hopefully this won't be as crowded as Catbert's June trip.