Cruise Critic has a series of articles detailing River Cruise Lines in depth and comparing them head to head, for which I will try to keep up to date links here.  [thread updated July 23, 2023]     Best Active River Cruises [Dec. 31, 2018] http://www.cruisecritic.com/articles.cfm?ID=2610   Best Budget River Cruise Ships [Aug. 29, 2018] http://www.cruisecritic.com/articles.cfm?ID=2865   Best Luxury River Cruises [Sep. 12, 2017] http://www.cruisecr