(I just did Vienna to Prague this summer, and it was amazing. Great routes, good signage and lovely hotels.)
Yes; I'm hoping to get the route loaded onto the GPS before we leave, to minimize the frenzied last-minute planning we'll otherwise have to do in the little time we have in Vienna.
Have you seen a copy of the book you linked to? The reviews on Amazon seem mixed. Unless it has quite detailed maps it won't be very helpful. The route we want to cycle is a very small fraction of the Donaueschingen - Budapest route covered in this book, so I'm not optimistic it'll have the level of detail we need.
Last edited by mregehr; 08-17-11 at 02:47 AM.
Reason: consolidating replies
Perhaps you have already left, just for people who might be wondering: I did part of the Danube route last year while cycling from Vienna to Zurich, the part along the Route Velo 6 route was very well marked and very well known with the locals. They see cyclists as a very welcome addition to their economy. It's hard to get lost and people are very eager to help you on your way.
Locally you can buy very detailed maps specific for cyclists with trails to spice up the otherwise somewhat little challenging route. Accommodations are generally very well catered for cyclists. There is no need to worry if you follow these routes.