<p>The only time I was in Koln was for Fasching (Mardi Gras) which I am sure colored my view of the place! 
I also agree with the assessment that Berlin and most of southern Germany is more interesting than Koln. </p>
<p>I always found Salzburg a little too touristy (and I hate The Sound of Music which doesn’t help). But do go see an opera at the puppet theater and take a trip to see a salt cave.</p>