We took the Great Rivers of Europe cruise in 2010 from Vienna to Amsterdam. It was our 1st time in Europe, and we took most of the optionals and enjoyed them. We did not do the Documentation tour in Nuremburg, as there were many places we wanted to see in Nuremburg that afternoon. Only a few people took that optional, as the majority stayed the entire day in the historic center. Melk Abbey is stunning, not to be missed. The Bavaria, Baroque and Beer tour includes the Weltenburg Monastery, a Danube Gorge boat tour and a visit to the Liberation Monument, as well as a beer and pretzel in the Beer Garden of the monastery. Marksburg Castle sits high on a cliff overlooking the Rhine. The tour of the castle is interesting, and you get an excellent view of the surrounding countryside from the castle. However, if you have mobility issues, poor balance or a heart condition, you may not want to take this tour. There are quite a few steep stairs to climb to reach the castle proper from the parking lot, and there are many stairs in the castle. The entrance to the castle is an uneven rocky area, which is quite dark. Some people found this passage difficult. The program directors warned us that this optional was for the mountain goats. A smaller number of people took this tour, but those who did enjoyed it. We took the Musical Vienna optional on the Vienna pretrip. It was a tourist show, held in a lovely palace. My husband and I and the rest of our pretrip group enjoyed it. If you are a music critic, expecting a high quality performance, you might be disappointed. We are all individuals with our own likes and dislikes. As I said, it was our first time in Europe and we wanted to experience as much as we could in the time available. We were not disappointed. The Great Rivers is a wonderful trip. Enjoy.