I chose to take two years of Spanish in school but no puedo recordar mucho.
It would be either Spanish, so I could communicate with a lot of our population or Chinese, the future language of the US.
Mandarin and Spanish
Mandarin and Hindi
Irish Gaelic .... I've learned a tiny bit.
I'm fluent in two languages (English and Indonesian) but if I were to choose to learn more, I'd choose Korean (which I'm currently learning on my own anyway haha), Mandarin (which I did learn as a child but I should pick it up again), Japanese (which I learned a little bit on my own in middle school), Thai, and Arabic.
(1) Spanish and (2) French.