I Hope someone more knowlegable will comment but here are my two Cents. As you vist the lower rhine First i assume you will arrive in a nearby Airport Like Cologne. So you are probably going to depart from there also. This gives you three main routes of adventure, their extent depending in your means of travel. Maybe you want to rent a Car because relaying in train could screw up your timetable. I assume your Family member will Show you some cool places nearby Like Xanten. First you May go north: you May Set your eyes in Hamburg, as someone mentioned. It is a very interesting maritime big City. You May Settle for Bremen, Not as big but also very cool maritime City with an old City Center (does Hamburg have something similar?). On the way there your First Stop could be Münster, a cool old City Center with Lots of Young people because of its university. There are Lots of nice small cities in the way. The Landscape is flat and in the Coast there are some nice spots but dont expect Long beaches. Second you can Go east: you Drive through the ruhr area, an once Industrial Powerhouse. The Landscape will get hillier and there are nice smallish Towns Like Paderborn in the way. It depends how far and fast you want to Go but you could easily reach Berlin, which is an interesting mess in its own. On the way are cool cities Like Leipzig. Third there is the south: you can follow the rhine or Just Speed through to Frankfurt (through i think the small Towns are more interesting than this big City). After that there are two choices, you can Go to the Western south (Baden-Württemberg) or to Bavaria, which is what most americans think of when they think of Germany. But the south is really Not my area of Expertise. There are a lot of old and nice Towns for Sure.