I talked about this in my last post but wanted to post a separate post for those who wouldn't read my post.
Deutsche Bahn has something called a Länder-Tickets, which is a regional day pass. For under €30, up to 5 people (or parents and all children under 15) can travel anywhere throughout the region from 9 a.m. until 3 a.m. of the following day.
If you are planning to stay in one state for the day, it might save some money over using a day on your railpass.
Länder-Tickets information