The simple answer is yes, San Anselmo is an ideal place to raise children.
Let's break down your typical day. In the morning, there are some great local options on San Anselmo Ave for breakfast, coffee, tea, or bagels. From there, you have a number of good walking streets that can lead you to a number of parks, creeks, or trails. San Anselmo also has a number of great lunch spots or shops for afternoon shopping. There are generally enough kids around that your child can find a playmate. You have movies in the park in the summer time, which is a great for kids and parents. There also a number of street festivals in San Anselmo.
You are also a close commute to so many other great towns: neighboring San Rafael and Farifax, beautiful drive West to Pt. Reyes, camping just 15 minutes from downtown San Anselmo, and so much more. I would encourage spending a couple of days in San Anselmo to experience it for yourself.