I grew up in Spain, from the age of 4 to 17 - so I am a bit biased.
The people are incredibly friendly, the food is wonderful, and history hits you each time you turn around.
I was in Barcelona for a few days last week and this city rocks. I lived in Madrid as a child, and didn't know Barcelona well. There was no low-cost travel, so it was 'at the other end of the country' and because mostly of cultural differences, people from the two cities didn't always mix. Now, Barcelona is such a thriving place it has its own direct flights to such places as Newark, Buenos Aires and Singapore. Talk about a world class city!
While many of my friends were sitting back home in the freezing cold and even snow, I sat by the pier, in the sunshine, having an outdoor lunch of fresh seafood. Granted, the city isn't cheap, but prices are standard for Europe. There's plenty to do - I took the 'hop on, hop off' bus and could have continued hopping for a week!
Other favourite places? Malaysia for the food and scenery, Denmark for the sense of humour of its people, Brazil for the rainforest and lilting language... in fact there's hardly a country I've visited that I wouldn't go back to again, for one reason or another!