Du borde kunna besöka ett Schengenland som Spanien för turism eller företag i mindre än 90 dagar utan visum.
Från US Department of State Bureau av konsulära frågor :
Spain is a party to the Schengen Agreement. This means that U.S. citizens may enter Spain for up to 90 days for tourist or business purposes without a visa. Your passport should be valid for at least three months beyond the period of stay. You need sufficient funds and a return airline ticket. For additional details about travel into and within Schengen countries, please see our Schengen fact sheet. Visit the Embassy of Spain website for the most current visa information.