Essen is quiet a town... I'd invest some time to visit Villa Hügel, the former residence of the Krupp family, now a museum. It's in a beautiful park. But in the neighbour city Bochum, no 20km away from Essen, you'll find the famous Starlight Express musical. In Dortmund you'll find the biggest casino in europe. Hattingen has got the beautiful castle Blankenstein. Anyways you're in the capital of culture 2010, in the Ruhrgebiet. There are many places you can go.