Regarding Viking River Cruise - My wife (Carol) and I will be on the July 15th sailing as well - From Kelowna, British Columbia, Canada.
A couple weeks ago I came across an excellent, 30-page write-up, by a lady who took a recent trip on the Vantage River Navigator, which sounds very similar to the upcoming Viking cruise. She starts in Prague, but by the 3rd day begins the cruise out of Budapest to Amsterdam. Here is the link, which I found most interesting and useful.
In case the link does not work, go to:
click on "Miscellaneous Reviews (river boats & barges)",
then on "Vantage River Navigator".
Hopefully we'll meet both Louise and Sparky on board!