Dubrovnik was like a Game of Thrones theme park the only time I visited. Kotor is a much more interesting walled city. And if you can sail into it or out of it, that's incredible.
Salzburg is ok. I tend to think of it as a work city cos I've only ever been for conferences.
Graz is nice, as is Bern, Belgrade, Tallinn, Helsinki, Krakow, Munich etc but I don't think they're as interesting for a flying visit as the others I listed.