Best City in Europe to Visit

I'm starting to get really geared up for this move, and in particular, I'm excited about the prospect of travel around the continent. I mean, if we're going to be in France, we really should take advantage. There are a number of places that I really want to visit while we're over there, such as Barcelona, Athens, Berlin, Lisbon/Porto, Edinburgh, Budapest, Sicily/Capri, Istanbul (no Constantinople), Sofia, etc. I think it's important for us to decide what is tops of our list, and I figured why not open this up to all of our friends to let us know the places that they really liked/hated. Now this in no way means that we will actually visit the spot you suggest, and we may well decide to visit the places you hate. I'm just hoping for some input, and maybe some information gleaned from personal experience about what there is to do in these cities and when we should visit. So, I open the forum to all of you, leave your comments and we'll certainly think about looking at them.