We used to have ridiculously cheap off-season international flights in my hometown, so I'll comment on a few of the locations mentioned as overrated.
1. Paris and Barcelona; just a walk and a meal in either of these locations will fascinate most anyone unless the person has absolutely no interest in art, architecture, food, wine or history(not a criticism, just a warning against wasting your money if you prefer to just kick back at the beach with a beer).
2. Versailles - the wife and I did not want to wait for the long lines to get in the palace. We instead walked at our leisure around the grounds then into the town where we had a great lunch with wine with the locals who almost never see an American up close.
3. Miami - beautiful, beautiful women everywhere with interesting night life, Cuban neighborhoods and great spicy food.
It was a quick drive to the keys for days of revelry.
4. Munich - go there at a time other than Oktoberfest. The beer halls rock year round. The museums are prima and the accommodations are spotless.
5. Amsterdam - lots to do but it was sad to see so many beautiful, historic buildings with graffiti, while the walking dead addicts march about.
6. Switzerland - first time there with the family 2 years ago and even the train ride was interesting. We stayed on Lake Geneva with an old town, a new town and fantastic scenery.
Many of the foreign locales mentioned as over-rated improve immensely once you get off the beaten path and into the neighborhoods not always mentioned in Frommer.