As it happens I'm visiting (English) friends in Kassel next weekend. He works for WINGAS. They seem to have quite enjoyed their stay (they're leaving soon after 3 years there), and have quite a large circle of expat (international) friends, mostly through his work.
On previous visits, I've been to the very impressive
Schloss Wilhelmshöhe which is up for UNESCO World Heritage Site status. This place is home to those Rembrandt piccies and lots of other goodies. Had "Kaffee und Kuchen" at the Orangerie too, which was very pleasant. I got the feeling I was in a town rather than a bustling city.
Cheap flights to the UK with Air Berlin from Paderborn, and ca. 80 Euros for the train to Munich. I never saw a racoon either, but residents are advised to keep bins tightly shut.