Grandson_3's school has a unique requirement: in addition to the in-school foreign language class (which I believe is Spanish), they require families to do a foreign language at home. This language does not have to be the same as the in-school language. (This is a "school of choice", rather than a regular public school.)

Son_2 and his wife looked at the possibility of the whole family learning Mandarin, Hindi, Spanish, French, Greek, Arabic, Russian, and Hebrew. Having lived in SoCal for his growing up years (and having family members who married into a family of Mexican citizens and who married into a Puerto Rican family), he's always been Spanish-adjacent. I think we're going to try to increase the Spanish exposure while choosing another language.

Son_2 enrolled in a French course at the local college when he was in high school. He discovered that French is very difficult. (And he did it on his own, so he didn't take the section taught by the instructor I would have suggested ... who would have told us what we needed to do at home to help him learn it.) Anyway, he says French is too hard.

I suggested that whatever language we choose, we piggyback it on Esperanto, because one of the things that I found most difficult in my German and Spanish language courses was irregular verb conjugation (well, "case" and "gender" were hard concepts too ... the word for chair might not be neuter despite there not being a gender for an object). I think that learning a language without that issue will be easier and that successfully learning one language helps when one tries to learn another.