Originally Posted by Camel
I haven't been to Italy, Ireland nor the Netherlands (yet). If cycle friendly infrastructure and variable terrain is keen on your list of riding areas, do check out Austria/Germany(Bavaria) as well.
Xilios' idea sounds loads of fun as well.
What cites in Germany should I consider? I am looking for varied terrian as you said but not too mountainous. Also looking for castles. Decent weather.