VR00, we don't have kids in Cupertino but know people who do/did. This is what we have heard:

* very competitive environment with a large population of very bright and driven kids.
* regular mix of teachers of different caliber. There used to be a fabulous Science teacher who was pivotal in helping get her students to top ranking in Intel Science competition but I am told she has moved on to a gifted only school.
* some schools have eliminated GATE programs because almost all kids qualify.

That said, we see no shortage of parents paying million+ dollars even for small, old homes in the Cupertino School District.

Our understanding is that unfortunately there is no public school we know of in the Bay Area that is great for PG kids. We put our child in a public school environment knowing that most of his academic learning will happen outside of school - even with some accommodations at school. We hoped for a relatively safe social learning ground though.

When he started as a kindergartner, he could not comprehend why his classmates did not engage with him mentally at the "fun" level. A wonderful gift of him being in a public school is that he has learnt to cultivate humility and have empathy for children who struggle and finds ways to connect with them that are not necessarily academic. Recently he came back from school and exclaimed, "Mom, Sarah is an amazing artist! She is even more gifted at art than I am in Math!".
Also, easier academics has freed up time for him to focus on a time consuming extra curricular activity that he loves.

As far as differentiation, it is very hard to find enough PG kids for a thriving group for differentiation. Also, when teachers talk about differentiation, I will request them to clarify what they mean by differentiation. Unfortunately, often differentiation is just more of the same old or sitting alone and learning. Perhaps other parents have had a better experience.

If your child is a DYS, there are many here, as well as Lyceum of Santa Clara Valley, Math Circle and Mensa get-togethers all over the Bay Area. We have Tech Museum, Computer History Museum, NASA, many amazing museums in San Francisco, California Academy of Science etc. Also, some private schools specifically for the gifted (sorry no first hand information) such as the Nuevo School in San Mateo and Proof School in San Francisco.

Wishing you good luck!