Hi Cinema! Sorry for my late...
I red other's posts and...yes: if you want a cheap way to move from Spain to Italy (or viceversa) my suggestion is to use Ryanair (
Ryanair.com - Book your cheap flight, hotels, car rental with ryanair.com) low cost company good for short trip. Many times you can find 2ways trip where for the first trip you pay only 10 euros (for example) instead of the whole cost. Little note: Ryanair use airport usually far from the city center (for example for Milan: the airport of Orio al Serio is closer to Bergamo!) so check where you want to go and where the airport is!
About Alitalia (yes, is our flight company) I don't know what to tell you because Alitalia is having veeeery big problems and you can light on strike, delay or cancelled flights....its a drama!
Last year, when I flight from Milan MPX to L.A. I use British Airways with intermediate stop at London Heatrow.
You can use Expedia (Expedia.it or .com as you prefer!) to check tickets price!
The most compllicated thing is, in my opinion, on choosing th hotel: Italy (I think Spain is the same) is very expensive on bedroom. Is not the same in US where you can easily find a room for 4 people at the price of less than 100$ for room. The best thing is to choose a city/town and ask if someone know some good and cheap hotel!
Another tips: If you want to rent a car, remember that gasoline is veeeery expensive in Italy! Than you need an Italian translation of your driving license and..remember also that Italian bigger streets has usually no more than 4 lanes, not 8 or 10 like in US!!
Ask about any dubts!