All of the top ten most expensive cities in the world, except Reykjavik, make the top fifty. So even if money doesn't buy you happiness, at least it gets you quality of life.
According to the survey, the best places in the United States are (in order of ranking): Honolulu, San Francisco, Boston, DC, Chicago, Portland, NYC, and Seattle. Of interest, Mercer also provides a ranking of "health and sanitation." Pittsburgh is tied for tenth best in the WORLD.