If you still plan to take the ICE, I see 2 other cities you may want to visit:
1. Weimar (Goethes home town, provides great exhibitions about him and his aera)
2. Nurenberg (great castle and very very nice old city, great Museums too - esp. Verkehrsmuseum & Spielzeug (toys) museum)
Esp. Nurenberg is well worth a visit.
If you got any questions left, please feel free to ask...
Greetings from Germany
McKaye