I am from Argentina but have been living in usa for quite a while i am 20, and a few days ago I was introduced to two Spaniards and when they offered their hand, I pulled them and gave them a kiss on the cheek. They didn't object or give me a funny look. We do this in Argentina, and I will be visiting Spain soon, so I don't want to do anything that will get me punched. We are all heterosexual.
It's more common to shake hands, kissing on the cheek is usually for family