I have to say - after the "madness" of taking trains, taxis and hotels in Europe just to visit Salzburg, you can't beat a cruise - either by riverboat or cruise ship.
Our train ride was madness. We had to run to get on the right car on our first train. It was an August friday, so the station announced that the train was full and there were no gurantees you would get a seat. We did - foryunately, but that is the way they sell the trains - no guaranteed reservations.
On our train change in Munich - we had 14-minutes; NO time to even double-check the track number on the monitors. We had to RUN from track 23 to track 11 (as our reservation said). And when we got there we had to run to the section 2 of the train. We had doors slamming shut in our faces. We finally jumped into one car and sat down, my wife & I about 20 rows apart. We only jumped on because track 11 happened to say "Salzburg."
It was packed & hot. Then we had to get a taxi to the hotel ($$) , we had to buy dinner in restaurant ($$), etc. This is not way to see Europe! Stick to cruises, really!