Wow...some really negative comments on here which are completely incorrect and untrue.
I'm guessing that the original poster is either of German ancestry or has spent some time living in a German speaking country as a child. If this is the case then moving to a German speaking country for you will come without any surprises.
I moved to a German speaking country for my first job and so far its been great. I certainly earn more than the guy pumping the fuel and I'm definitely not a loner!!
German is probably the best second language to have as an EU passport holder. Austria, Switzerland and Germany are all covered here. All three countries are strong and stable with lots of job opportunities at each level. Switzerland offers salaries higher than the UK, Germany around the same (when you adjust for the reduced cost of living) and Austria a bit lower (However its a cheap place to live).
I see that some posts on here have mentioned the low salaries on offer in corporate aviation. This is generally only true on the small business jets (citations etc), once you get onto something bigger you will earn good money. This won't take long, maybe a year or two tops. As I've mentioned above the cost of living in some of the German speaking countries (Germany and Austria) is lower than the UK and salaries reflect this, however you will still achieve the same general standard of living as your money will go further.
In conclusion, I believe that any second language is of benefit as long as you have the right to work in a country where that language is used. The issue we face as Brits is that everyone can speak our language and the whole of Europe can apply for our jobs!