For some reason, a lot of Mexican Spanish speakers here seem to prefer ¿Qué pasó? to ¿Qué pasa?. I've no idea why.

I have enough communication problems already (the other day, I threw one of the servers for a loop by asking for fideos, which they all seem to call noodles) that I try to avoid anything too marked as Peninsular, so I almost always replace vale with está bien.