For men I would use caballero or señor :
Perdone caballero, me permite una pregunta?
Disculpe señor, sabe donde esta esta calle?
For women I would use Señora or Señorita. The first is used to married women, and the second for (younger) unmarried ones. Since yo can't tell, unless they are blatantly old I would go with Señorita (middle aged women won't mind to be addressed like Señorita, trust me).
If you want to be informal (e.g., your work buddies or friends, in a relaxed environment) you could use tío or colega.
Tío, me acaba de decir el jefe que nos doblan el sueldo.
Eso no te lo crees ni tú, colega.
If you want to go even more informal than that, you could use tronco.
Dame un cigarro tronco, que me he dejado el paquete en casa.
Don't use varón, because that is Spanish for male (And you don't say "Excuse male, what's the time?, do you?)