My favourites:
Siem Reap, Cambodia (loved the history)
Lake Ohrid, Macedonia (beautiful and the people are lovely)
All of Tuscany, Italy (the history, the scenery, the people)
Berlin, Germany (the history, the charm, great city)
Montreal, Canada (charming, old world meets new)
Nova Scotia, Canada (absolutely gorgeous)
Newfoundland, Canada (so remote, so empty, icebergs, moose)
Zermatt, Switzerland (the Alps)
Shanghai, China (east meets west)
Xi'an, China (historical, people very friendly)
Nearly everywhere in Thailand (lovely people, lovely food, ultimate relaxation break)
Barbados (lovely to swim off the shores here)
Worst:
Geneva, Switzerland (so expensive for not very much)
Munich, Germany (no charm, not very nice people)
Auckland, NZ (very nondescript)
Rome, Italy (wow, so unfriendly; very dirty; even their awesome historical sites couldn't make up for everything else)
Brisbane, Australia (overrated, unfriendly)