I would like the developers to give Spain a good Rush strategy, I propose the following. 
MODIFIED Spanish Inquisition (Age II): Allows training Inquisitors in churches (Spanish Inquisitors count as archaic units)
TEAM Hidalgos (Age I): Improves the training speed of all archaic units. (The inquisitor and rodelero should also be affected)
NEW Spanish Adventurers (Age III): Replaces the dragon with the Conqueror and allows research, Flying Buttress, Smokeless Powder and Christian Schools in the church.
Note: The Conqueror can be upgraded from the stable like a normal cavalry unit and costs 2 population.