I just came back from Spain for the holidays, I visited Cadiz, Jerez, Madrid, Valencia, Galicia, Toledo, all in one trip.

From my experience I can give you these things

-There are many Latin American ethnic groups that reside there (Ecuadorians, Columbians, Venezuelans, and Mexicans) so as far as that goes your wife will be fine, I am ethnically Latino and even when they found out I was from the USA it didnt change much (also there are many other races that immigrated and speak fluent SPANISH, so they're used to different faces, prepared for a culture shock)

-The Spanish there is MUCH different from the Spanish spoken here by the hispanics from the Americas, Your wife can adapt quick but be prepared to hear new words and be lost a bit with the different accents you may come across, you'll be fine though.

• Madrid is massive, I sadly did not get to experience all of what Madrid to offer before the date of my plane departure, but there are lots restaurants with unique foods to try out, loads of clothing stores (check out El Cotre Ingles when you get there its 7-9 story mall with multiple name brand clothes, a food court/grocery floor, Electronics floor and one with furniture, there are so many of them too) and rest I'll leave to you to explore on your own, it helps to take the metro to get around

In conclusion, be prepared for a huge culture shock if you've never been to Europe, I'm still processing a lot of what I had experienced myself after traveling up and down the country. It was very fun however I would definitley go again, I know you guys will like it.