Brutal choices (so I'll cheat, but only a little). With full disclaimers (and the right to change the list as the wind blows).
TOO DIFFICULT, I give up... Make it stop!!!!
Hard, very hard, to limit it to 5 and I haven't even been to most that I want to see! But, here are a few to-date (ok, some may not qualify as a 'city', only a village or town):
1. Hallstatt, Austria
2. Prague, CZ
3. Cesky Krumlov, CZ
4. Yvoire, France
5. Honfleur, France
Do I really have to limit it to just 5???
Jerry, it was. Jiangmen is an "off the beaten path" town of 4.5 million (that's China for you!), about a 2.5 hour ferry ride from Hong Kong and an hour drive from Guangzhou. It's a "sister city" of where my kids go to high school and play in the band. They had a homestay with local high school band families, while us parents were treated like royalty by local school and city officials, and stayed in a great hotel. Lots of history in the area, great food (seafood, vegetables) and some of the friendliest people you'd ever meet.
Thank you, Jasper.
Perhaps that finding won't bring too many frowns to the faces of Marriott's strategic planners?
I recall a conversation about 5 or so years ago with a "senior" Marriott man who offered the observation along the following lines: " given cost-base trends, these days there were only three major cities in the world where the likes of Marriott could expect to develop a new hotel and make a reasonable profit - New York, Tokyo and London." When I saw him again a couple of years later, he added, tongue firmly in cheek: "and we were wrong about one or two in London!"