Time of year. We're gardening people and wanted to visit the areas to see spring coming to life. It was spectacular as we're all of the other sights. Guides were great. Interesting, knowledgeable and fun. Boat crew very professional and pleasant. We were treated royally. We liked it so much that we are going on a Viking ocean cruise in 3 weeks. The cabins were great although we didn't spend much time in them because we busy with tours and activities. Food was superb served by attentive and polite wait staff. They go out of their way to make sure everyone is happy at all meals. Tours/excursions were very interesting and informative. Ground transportation was very comfortable and efficient. We felt comfortable and secure everywhere we went thanks to thorough communication by the boats personnel. I highly recommend Viking River Cruises. We will most likely take more. The Rhine Cruise in spring is beautiful. We're anxiously awaiting our Viking Ocan Cruise in 3 weeks. I'm sure it will be great just based on how much we liked the river cruise!