Eric Weiner went on a quest around the globe to figure it out and wrote a book about it:

The Geography of Bliss – One Grump’s Search for the Happiest Places in the World

Watch him discuss his experiences with Will Wilkinson from the Cato Institute at Bloggingshead.tv, and listen to him talk to Diane Rehm or Rick Steves.

So where’s the happiest place on earth? Well, it depends on you after all.