Avalon Danube River cruise in December
 

We are scheduled for an Avalon cruise from Budapest to Vienna to visit the Christmas markets there. We embark on December 17th, and return on December 22nd. We have signed up for a few cruise excursions, but would like to hear from experienced/informed travelers as to some of their favorite destinations in the cities of Budapest, Bratislava, Vienna and Melk. Any help in this regard will be greatly appreciated...