Move from Napa to Walnut Creek for middle/high school?

We are contemplating moving from Napa to Walnut Creek. We have had a great experience in elementary school here, but feel the middle and high schools are not so great. Also, we seem to have reached the ceiling when it comes to kids' activities like tennis and piano. We are hoping to move the kids to better schools and more resources and avenues for extra-curriculars, but wonder if the infamous extreme stress experienced by Bay Area high schoolers is acutely present in Walnut Creek high schools, Northgate and Las Lomas. We want a good, well-rounded education for our kids, but not at the risk of their sanity and mental health. Any advice and suggestions?