Venice
All the other cities have spectacular natural scenery. Venice doesn't have that but more than makes up for it with bucket-loads of charm and enchantment. The beauty may be man-made but make no mistake this is a gorgeous city. Travel down the Grand Canal by gondola or spend a night or two at the Hotel Danieli and you'll know what I mean. Here's more on Venice.
Cape Town
Then you also have one of the world's greatest ocean drives, starting right in the city, and world-famous wineries downtown; wineries like Groot Constantia, which has been producing award-winning wines since 1685 and whose endless vineyards cascade down the slopes of Table Mountain.
Rio de Janeiro
Rio may seem a little wild and chaotic at times and I guess that's to be expected in a city that lives to the Samba beat. Still, if you let your hair down and party along with the locals you'll have a great time.
The beaches are the place to experience the soul of the city and take in its beauty. Combine a trip to the beach with a trip up to the famous Christ the Redeemer statue for the ultimate "wow" experience. Here's more on the essentials of Rio.