Independent Travel for Munich, Salzburg, Vienna & Prague prior to Avalon Danube Cruise

Sounds like a great time we are also doing an Avalon cruise Vienna to Moscow so since I have been working on our itinerary this is what I found most helpful. Have you checked out tour books Rick Steves and others have great one to three day suggestions. My husband thinks I'm the greatest tour guide as I plan 3 to 4 week vacations my secret? using these books my very favorite is Rick Steves because of the day walk and museum guides and Fodors See It because of the great photos. Vienna I got us Sissi tickets so we can get into both Hofburg Palace and Schonburn Palace without long lines or being turned away due to sold out dates. We will do Rick Steves city walk, enjoy the opera in the open if available if not catch a concert. We also have several days in Munich that Avalon covers well so will just chill and do local museums and parks. Hope this Helps

You can find a lot of great ideas in Rick's programs on each area and you can watch them for free. I agree that Rick's guidebooks will give you a lot more specifics so that you can better decide what is most important to you. A chauffeur service anywhere will be very expensive but Rick will give recommendations for transportation from airports, train stations, etc. Many places you mentioned are easy to connect with rail and you can find more information at Rick's Rail Page.