Learning a language for business

My wife and I want to retire in Ireland. She will retire before me, so I'll have to work when we get there (we've lived there before, have citizenship, etc), and a whole lot of jobs in IT (which I do) require a second language. I was thinking that learning German would probably be a good bet. Are there programs out there to help with learning a language from a "business" or "working" standpoint? Is Rosetta Stone a good program? Should I take one of those adult education classes that colleges offer (no credit, just for fun type ones), since those would be in person and interactive?

thanks, and I'll hang up and listen.