Learning a second language should be absolutely required for all Americans. It opens your head in so many useful ways. So good on you!

I did some work with Rosetta stone when learning Japanese. It was ok, but once I started actually using Japanese I found it hadn't been all that accurate. For beginners, it was good because the spoken and written language are connected right away, but once you move higher, it is not as useful.

I can't really say much about Chinese, except that if you ever want to be literate, START FAST. Those Chinese characters are not easy to take on.