The previous posters already made excellent recommendations.
I have last week been to the Technorama in Winterthur/CH with my 13yr old nephew and he was blown away. We went a second time in the same week - he was just fascinated:
www.technorama.ch
Another fun suggestion: Europapark Rust, about 60 - 90 min South of Heidelberg an A5:
www.europapark.de
Enjoy!