Arsen said:
Chapper said:
Where's Spanish?
I'd choose that, because then you're understood in all of Central- and South-America (except Brazil) and Spain, of course, which is a popular tourist destination.
EDIT: Are we limited to Europe only? If then I'd say German too.
Primarily Europe, yes my good man.
The reason I didn't pick Spanish is because...well it'd be expected of me to use my skills in using that language OUTSIDE of Spain. And Brazil's (the one good place in South America) primary language is Portuguese.
Being Portuguese myself I can say that, if you speak Portuguese fluently you'll also understand Spanish. They're very similar.
Personally I'd say that it depends a lot on where you wanna go really... As a tourist going everywhere all you really need is English, as it is spoken in most places as a second language... If you absolutely must, possibly French as much as I hate it...
If, on the other hand, you intend on living somewhere, learn the local language off course.