We are interested in the Rhine/Main/Danube river cruises. However, they are very costly. Having lived in Germany before, we think that we could make a pretty good driving trip and see more on our own. I wondered if there were any driving guides/books to outline such a trip-amsterdam to Budapest.
Dottie, The Michelin Green Guides are made for driving. You might have to buy a couple different ones to get the itinerary you want, as they are usually country, city or region specific.
If you're renting a car, the drop-off fees to drop the car off in another country could be prohibitive. You may not even be allowed to take the car into Eastern Europe. You might consider a mix of cars and trains, in order to return each country's rental car (rent a new car in each country). Also, you might consider leasing a car - how long will you need a car?