Work permit

I am an American citizen with grandparents that were original Spaniards and a father that is a spanish citizen (born outside of Spain). For Americans, it is very difficult to get a work permit in Spain because it must be proved that neither a Spaniard nor a citizen of an EU country can perform the job in question. In short, I wanted to clarify whether or not I would be exempt from assessment of the national employment situation due to my ancestry.

Yes, due to your ancestry you would be exempt.