Hello fellow expats! Many of us are starting to look toward making spring break plans and as I was thinking of places I’d like to go, I realized I had no idea if I’d need a visa to go to some of these places. Luckily the American Dept. of State passport office has a very easy-to-use site that breaks it down and also has any travel alerts posted. With your current NIE from Spain you should be fine traveling within the European Union, including countries that are part of the Schengen Agreement. For non-Americans, a quick Google search will bring you several resources to check for your respective countries, like this one for British citizens.
Another thing to keep in mind is that some of these discount airlines offer cheap flights, but sometimes the airport is pretty far out from the city. For example, Paris has three airports in its vicinity. However, one of these (Beauvais) is more than an hour from Paris itself. So, double-check the location of the airport and how to arrive at your destination. You might find a really cheap flight, but by the time you buy a train or bus ticket into town, it could be cheaper (and more time efficient) to fly to a more centrally located airport. And speaking from experience, I have flown to some of these outskirt airports before and if the flight is delayed and you arrive late at night, it’s possible that the public transportation system will be closed and you’ll have to take a taxi.