Not latin. You get some of French spanish etc but you might as well learn one of those languages directly and get some use out of it. Latin is not useful on its own anywhere, and it's dead hard. Why bother ramming home the finer points of a grammar that no-one cares about?
I'd say French or Spanish. French mainly because out of all the European countries I can think of that's the place you're least likely to meet an English speaker.
It's hard though for an English speaker, since it's intonation and subtleties of inflexion are hard for Anglophones to manage. German and Scandinavian etc are much easier from this point of view, but if you learn how to listen and pronounce French properly you've had practise in a difficult skill (that is, understanding subtleties that aren't in your language). Learning German won't teach you this.
Gerard Depardoo (Alan Partridge content) at 2:40 in. Or you could listen to the whole sketch cos it's genius