1) The vibe in Barcelona is very much like New York City.
2) Spaniards don't tip waiters well, but they don't hesitate to give a beggar or a street artist 5 times the amount they give a waiter.
3) When a man comes to Barcelona alone, he is perceived as someone who wants to see Barcelona. When a woman comes to Barcelona alone, she is perceived as... someone who wants to see Barcelona.
4) You can sit down at a table at any cafe, order only a coffee and stay as long as you like. Waiters never give you a check before you're finished, in fact, it's more common to have to track him down.
5) Sometimes, when I'm introduced to a Spaniard, they ask me where I'm from. When I answer, "Estados Unidos," the person's smile drops ever so slightly. But when I tell them I'm from New York, their smile returns. (They will also like you if you tell them "No voto George Bush." That will work too.)