My mother tongue is Spanish, but I also speak French, and a bit of Japanese (We are located in Prince Edward Island, the Japanese love it here!) I took the time to learn the basic greetings in German, Italian, and Chinese, as those are my most frequent customers (outside the English and French community.)
Language is a complete game changer when it comes to service. There have been many circumstances where just being able to speak the language of an irate customer has turned the whole situation positive. Even at check in time, I've had cranky guests suddenly perk up just when I say "Guten Tag!" They understand that I don't speak the language fully, but they appreciate that I took the time to learn a few phrases.
If Innkeeping is something you want to do for the rest of your career, I really suggest picking up a least another language. I'm in the process now of ameliorating my Japanese and German (Italian and Chinese can take a backburner for now.)
I find Rosetta Stone to be an AMAZING tool to learn a language fast and efficiently, but the best way to learn a language is to do it with a friend, or spouse, so that you can practice conversation. It's also more fun that way!!