Everyone on the Fodors forums are constantly asking about wearing jeans in Europe.
Just to let you know all I see here is jeans, jeans and more jeans. They are worn in every style you can imagine. Tight, loose, boot leg, taperd, embelished, cargo, low rise, high rise, you name it.
In all the restaurants I visit the waiters wear jeans, the people eating wear them, everyone seems to have the latest styles and designer versions.
If you don't wear your jeans you may actually feel out of place.