My favorite park in Europe is Europa (between Stutgart and Strasbourg, France). Also Phantasialand near Cologne and Heide Park (near Hamburg) are both really good. Holiday Park has a very good rollercoaster. There are another half-dozen decent parks and many smaller ones.

There are some great cities for castles and medieval towns. The whole area from Munich to Neuschwanstein castle is very beautiful. Rothenburg is a great old city. Heidelburg is great. So many cities along the Rhine are awesome. It seems that almost any city in Europe of any size has a great old town.

And the food is great as mentioned.