Spanish Style Homes are often of the 2 story variety… and the stair case is located in the formal entry of the house.
Using wood for the banister is the usual choice… even in hacienda style homes. But… iron railings were popular in the 1029\'s and are still popular today.

They may be more difficult to create… but the iron is easier to maintain… has more potential for dramatic staircase design and the ability to have fantasy custom wrought iron is a plus!