El Sobrante elementary schools

No firsthand experience but as another parent in the district, I can tell you Valley View has LOTS of political juice associated with it and they always seem to get what they want from the school board. I'd have no hesitation to go there if it were my neighborhood school.
 

You are likely to have a tough time finding these because Great Schools ratings correlate most strongly to student income, and income is tied housing cost. There are some outliers, but most of the 8+ schools rate that highly because the socioeconomic status of their students is much higher (= more likely to have gone to preschool, have parents who are college educated and in stable jobs, have stable housing, etc. which all contribute to higher test scores). This is reflected in the cost of homes in the area zoned to the school. El Sobrante is a far more diverse community, and this is reflected in both the housing cost and the school test scores. So the first piece of advice is to look at the schools that rate 5 and 6 too. There are many in that area, and many are well loved. We have friends who have had a wonderful experience at Valley View, and I've heard good things about Olinda too. Go and visit the schools in person to see which you like--don't go based on test score alone. (Same advice applies to Oakland and Berkeley, for what it's worth--many schools that don't have 8+ ratings that are nonetheless wonderful and in high demand.)

My advice is to try to talk to parents at the schools you're thinking of. Those Greatschools ratings are based a lot on test scores, and schools with true diversity include a lot of English-language learners. In my book, that makes them a better school than some lily-white enclave where everyone comes from a privileged background. Look past the ratings and talk to parents at the schools. 

You have to go on more than just the overall Greatschools ratings, especially since they have reconfigured their system within the last year or so in a way that heavily counts against schools with a high number of special needs, low income, or EL students.  Take Olinda in El Sobrante, for example.  It's overall Greatschools rating is a 6, but the test scores for not low-income kids are a 9.  If you're not low income, which you aren't if you're able to buy a house in the area, your kids will be more than fine.