Hi Jaime! I think Paco65 has THE BEST idea. BUT, try to name 1 or 2 companies in the USA FROM Spain? I'm sure they exist, but I can't think of any. It would certainly help the transition to their headquarters in Spain.
Also, keep in mind the extremely HIGH unemployment rate in Spain AND the law that says all companies must first consider ALL Spaniards for job before looking elsewhere. I wish you the best of luck, but I think, maybe, your goals are a bit too high. I too would want a job in Spain that would allow me to travel.. and I'm sure they exist, but I would think most of those jobs are going to THE TOP, THE CREAM OF THE CROP! Hopefully you are one of these people.
Along the same lines, having been asked this question about a thousand times ("Hey! Why don't you try to get a job with an 'American' company in Madrid?") and after spending years looking for ways to find meaningful work in Madrid, I have
some knowledge about this topic.
While I haven't physically visited any 'American' company in Spain, it's my strong impression that if I did I would see that probably 90+% of employees would be Spanish and the rest, nearly, are fluent in Spanish and European nationals.
How many Japanese nationals work in the Honda car manufacturing plants/factories here in Ohio/USA?? Probably almost none unless they're in higher management. I believe it's the same in Spain.
Again, my strong impression is that if I wanted to "go that route" I would have to start working for "XYZ 'American' Company" here in the USA, work for several years and work up to a position that could allow me to have a "temporary assignment" in "the foreign office".
I could be totally wrong (and hope I am), but..... Best of luck!
Saludos, MadridMan