Spanish at Berkeley High
I definitely recommend that your child get started with Spanish, especially if she is not being academically challenged. That way, once at Berkeley High, she may place into a higher level class at entry, and be able to take AP Spanish and/or AP Spanish Lit later on.
My child's Spanish teachers at Berkeley High were good to excellent. Same for the English teachers. Not so for the Math and Science teachers, unfortunately.
If you want to advance through advanced language classes in high school, taking language in middle school could be an advantage in that it gets you into a second-year language class as a freshman. But if your child doesn't know yet whether that's something they want, it may not be a real motivating factor.
My daughter took Spanish for two years in middle school. It was pretty mediocre (not at all academically challenging.... she too was not really challenged in middle school) and she didn't feel like she learned much. She's had a better experience at Berkeley High, but still not great. She's a sophomore and doesn't want to continue with language after this year.
I guess the advantage for her is that she now has 3 years of language on her transcript, basically and can focus on other interesting classes/electives at Berkeley High.
So maybe it's sort of a decision of whether to have that opportunity in middle school or in high school.
Also, if your child is interested in languages other than Spanish and French (I think at some Berkeley middle schools only Spanish is offered), there are more options once they get to Berkeley High.
Two years of middle school Spanish allows you to skip one year of BHS Spanish--so starting in Spanish 2 instead of 1. It's not a huge advantage. Your child will undoubtedly take language in high school and whether she starts with 1 or 2 isn't a very big deal. I've had one kid who did middle school language and one who didn't and the one who did has more regrets because she thinks she would have preferred some of the electives.