I have done a river cruise with Viking. On the Danube. We had a nasty problem at the outset ( were supposedly on the wrong boat.!) which was caused by their Swiss agent. My (then )TA in Zürich sorted it and we transferred to the "right" boat. And it was a great cruise. However not as good as the Deilmann cruise we did the next year on the Elbe. Now that was a really good river cruise line!! Sadly they do not do any river cruises anymore.

I would be interested in Uniworld... IF Ngaire recommends it. And we can most likely take the train to the boat and back...