Bochum is beautiful, if you go there some day you can't miss a soccer game-- these people are so dedicated to their team, it's a great experience. You also have to see the Rhine river and take the lifts up the hills over all the vinyards, if you do I promise you will not be disappointed.
The oldtown part of Dusseldorf rocks.
Fly really cheap to anywhere in Europe with Germanwings from the Cologne-bonn airport!
I visited Blankenheim from 1976 to 1985. I loved the people culture and city. I would love to return to see frends like HUBERTA MULLER - firstname.lastname@example.org.