If I answer this question from just-for-fun standpoint, I think I’d probably say French. Or German.
French just seems like such a fancy language to speak. I could pretend to be sophisticated!
And German is appealing to me because I have a lot of German heritage.
BUT.
If I think about this from a practical “How could I best serve others?” perspective, I think I’d choose Spanish.
Do you encounter French and German speaking people in the U.S.? Sometimes.
But Spanish-speakers are far more common, so I think Spanish would be super useful.
And if I ever do pursue my nursing career dream, I can see Spanish being much more practical than French or German.
I will be a little surprised if I manage to make the time to learn a second language, but who knows?
Maybe I’ll get really bored once I finish homeschooling (Zoe graduates in three years!), and my brain will need a new challenge.
And Spanish would certainly would be more enjoyable than all the algebra challenges my brain currently faces. 
I haven’t signed up for this yet, so I can’t verify it works, or that there’s no commitment after 3 months, but I thought I’d pass it along in case you wanted to get started early. I would also love to learn German, but agree that Spanish is much more practical.
https://www.rosettastone.com/freeforstudents/
Thanks for sharing but it looks like it’s only for K-12 kiddos, is that correct? I have a college sophomore who would like to brush up on his Spanish, but it doesn’t look like he qualifies. Am I missing something?
It says, “Not a student? Not a problem.” So, it seems they won’t make you prove it’s for a student.
I used to speak Spanish fairly well, but that was years ago, and I’ve forgotten a lot of it. Sure would be useful here in New Mexico, though . . .
To me, the reason for wanting to speak another language is to connect more with other people, so I have to look around me now, as well as look into the future (as much as possible- lol!) to try to see what would be best. For me, it’s also Spanish, and it helps while working in healthcare, as well as MANY other places. Basically everywhere, these days, at least where I live and work! There are many more Eastern Euopean-born people now, too. The gratitude and assistance I get in my attempts to speak in someone’s native language are so heart-warming!
I took Spanish class for three years in high school then CLEP’d out of 2 years for college Spanish years later. That being said, I’m nowhere near fluent. It’s really hard to learn a new language after age 9 or so (sources say 6, 12, etc.) Immersion/daily use seems to be the only way to speak and understand well. I’m pretty good at reading and writing, which isn’t as helpful.
What I have also gained is humility and the understanding that it’s very difficult and quite mentally exhausting. I can’t imagine how hard it would be with limited schooling, hunger, fear, relocation, poverty, working many hours, and the possibility of hostility from people around me.
Right now things are different, but “normally” around here there are various classes for adults to learn some basic Spanish or English, and some more advanced learning. Libraries, some churches, and community college are the main ones offering it. I know the only way to get to my goal of connecting and helping is to practice, like anything else. There’s a “formal“ conversation group in the bigger town where they meet weekly to practice whichever language one is learning with a partner or in a small group. I’m a little anxious and a little lazy, but I hope to overcome that!
Arabic, because I love how the written language looks.
I have been learning Spanish through the free Duolingo app for almost a year. I love it and am learning more and more even though I am only able to practice about 10 minutes most days. I had the same thinking, that it would be the most useful for where I live.
I was going to also recommend Duolingo. I took two years of Spanish in high school and not much of it came back, but in the less than 2 months I’ve been on duolingo, I’ve passed the point of review and have moved on to new material. I spend 5-15 minutes a day on it.
During my teaching career I learned American Sign Language which is now considered a second language. I have a certificate in Deaf Studies and American Sign Language. It’s never too late to learn.
I’d love to know Japanese because of the large amount of film and literature I’d love to be able to enjoy without translation. I’d also love to know French because it’d be something my father and I could speak together.
I’d go for Chinese. My in-laws love in Hong Kong and we got to visit a couple of years ago. I have hopes (though not high hopes) that we’ll be able to return someday and it would be fun to be able to speak Chinese if we went. A lot there is in English, but not everything and most of the older people do not know English.
German, for the same reason you gave for wanting to learn German – my dad’s family was extremely Deutsch!!! I had 2 years of Spanish in junior high, and 4 years in high school, again, for the same reasons you think it would be a good choice – Spanish is much more likely to be used here. I don’t get to use it much, but I’ve used it on vacation in the Caribbean, and here at home at Taco Bell! For a while, I used to listen to an all-Spanish radio station on the way to work. It was amazing how much I was able to pick up that way.