We had seen Budapest for a few days prior to the cruise, so we opted for the "Open air museum", which was 15 minutes in the countryside to a recreation of Hungarian village life in the time just before the industrial revolution. Our group was very small, and our guide was wonderful. Not a good tour if this was your only day in Budapest, but if you have seen the city, this was a nice day out in the country.
We did the optional tour to Cesky Krumlov. It was a long bus drive, but beautiful scenery. The town is a tourist trap, a lunch that was adequate, too much free time and a long bus ride back to the ship. Don't believe the guides when they say you can use Euros everywhere expect the museums and bathrooms.
We all did the evening concert, a very nice experience, much better than I had expected.
The next day we did the optional Bratislava tour -- walking tour by a well-informed guide, with some free time. 1.5 hour bus ride from Vienna.