Münster looks interesting and I've been scoping out some options there since it's so close. The Dortmund trip just allows for a full free day and some evenings--the evenings may need to stay local but a day in Münster would be doable.
I do love the idea of the cookbook/homemaker museum--I couldn't tell if it was open or was now more of a library but the pictures were intriguing.
Thanks for the suggestions!