I travel a heck of a lot and can honestly say:
New York - Felt claustrophobic and incredibly busy, ridiculous tax system and generally found people rude.
Rio de Janeiro - Beautiful Beaches, Sugarloaf is amazing but the actual city centre is very dangerous and there's not a whole lot to see. The poverty is also heartbreaking.
Venice - A bugger to get around, incredibly busy and hard to find many places that serve great food at an acceptable price.
Dubai is a wonderful city, if a little expensive. I did a jet-ski tour going past Burj-al-Arab and Atlantis and it was just incredible. I found the people there to be softly spoken and really friendly.
Paris is my favourite city in the world but it does help to make an effort by speaking French. Head for the restaurants in the main tourist areas and you'll be treated as a tourist and most likely ripped off. Speak to any gypsys bothering you with clipboards in French and they won't bother with you.