I like neighborhoodscout.com. Darker blue is considered as a better neighborhood. If you still need help to find a home, please feel free to call me. I would love to assist you. I have a listing coming soon in Pleasant Hill close to Lafayette and Pleasant Hill border. It's a beautiful home in a great neighborhood.
Following up on what Steve said, the neighborhoods that fall closer to the Walnut Creek border (rather than the Martinez side) tend to be in higher demand. Of course with a higher demand, the prices tend to be a little higher as well. I know a lot of my clients have been focusing on neighborhoods such as: Poets Corner, El Dorado Park, Gregory Gardens, and Grayson Woods. Most of them due to the close proximity to the freeway and BART while in safe-family oriented neighborhood. Grayson Woods has a public golf course near it, but is probably the furthest from the freeway. Depending on what your price range is, will most likely dictate what areas you can afford to look in.
As far as schools, you can visit: http://www.greatschools.org/california/pleasant-hill/ to see rankings. Also, just a heads up, Sequoia Elementary and Middle schools are on the proposed budgetary cuts for this year. Nothing has been officially decided, but just thought I would let you know.
If you have any other questions or want any other insight, feel free to drop me a line.
As far as traffic goes, look at neighborhoods that are not on major streets like Pleasant Hill road or Taylor Blvd, or Contra Costa Blvd. Also, keep in mind that the closer you are to the school, the more traffic will be around for dropping off and picking up students. Please let me know if you have further questions. I will be able to guide you in the right direction for your needs.