SPAIN, especially since you're traveling in the summer. Why?
EL ENCIERRO
(the running of the bulls)
That's right.
The greatest party on the planet. Head to Pamplona (northern Spain in the foothills of the Pyrenees) in early July for the Festival of San Fermin.
You party all day.
Eat great tapas, bacalao, paella, leche frita, flan...
Drink great rioja, albarino, patxaran...
Eat great churros (dipped in a mug of hot melted chocolate)
Dance in the streets all night.
Run with the bulls in the morning (8am sharp!)
Catch some sleep.
Then do it all again.
I've been to San Fermin 3 times. It's freakin INSANE.

While you're up in the North, swing through Bilbao and San Sebastian to experience the Basque people, foods, and culture. Incredible.