Hi there there are many places worth cycling in Europe. Some of my favourites are Provence and Cote d'Azur in France, north west Spain ( Pyrenees, Basque Country ) or Switzerland, Austria Italy along the Alps if you like great climbs and stunning scenery. You can read my travelogues
here
Also search and read about others experiences as it is the best way to plan your tour. My favourite websites are
www.cyclingtheworld.org and
www.raph.nl
Good planning!