My boyfriend and I are travelling to Germany in August and we'd like to visit different cities during our stay (3rd - 8th August): Düsseldorf, Köln, Bonn and Aachen. We are looking at different travelling options but don't really know which one is best and, specially, the cheapest! We've been looking at trains, but the fare does not always come up and it's also a bit confusing as there are countless number of trains and different prices. We've also considered the option of renting a car.
Any recommendations or words of advice?
Thanks so much in advance.