Marin County has all together has about 13 cities and towns. Each city has its own unique flavor or style and depending on what your needs are its hard to say which one is best for you. They all have their own little personalities. For example, San Anselmo is a great family community and bohemian and quaint, and close to all the things you mentioned above. Where as Sausalito is more of a boating community and I would say has fewer families in that area and that is also because the school district is rated a bit lower. You have to also consider the "weather" ,if that is important to you because if you choose Sausalito, Mill Valley or Tiburon you will have cooler temperatures and fog in the summer. If you go North of there the temperatures are much warmer and no fog in summer.
So it is really a more personal choice as far is what is the best city. Also, all the cities are in close proximity so parks and family friendly places are very accessible and each city has its own holiday parades, art shows, and events. It would be best if you came here and you were driven around Marin so you could see which is best fit and feels right to you.
I assist with Dominican University in Marin County with their potential candidates for deans. When they relocate here I give them a tour of Marin so they can see all the cities. The other thing to consider is prices. The highest price homes in Marin are Belvedere, Ross and Tiburon based on the best school ratings and location.
If your interested I can send you a relocation package.
I'd recommend letting us know what your price range is for a home purchase. There are MANY MANY towns in Marin that are extremely family friendly. The majority of our schools throughout Marin County are top notch (there are a few exceptions). Our county isn't all that big, and every town has parks, recreation, community involvement and more.
There are so many great places and if price is no object, then you can't go wrong with all of our communities. I personally can't pick one that is the "best". I tell folks that ask the same question that usually wherever you rent (if you rent first before purchasing a home) you'll typically end up in the same town as you start meeting friends, get involved with the schools and make it your home.
If you are limited by home purchase price then it's good to limit your looking in those areas that are more "affordable" and also family friendly. It REALLY does. depends upon your home purchase price.
if you are local, or are going to be in Marin coming up, you may want to attend my free Marin seminar that goes over EXACTLY what you are asking. I give an in-depth look at all the towns in Marin, talk about schools, weather, commute times, and more. Here is the link, there are 2 upcoming dates in May and June: http://www.MyMarinHouse.com
I'd also be more than happy to talk to you on the phone if you are not local and gear a "mini-seminar" around your specifics.
All my best,
(and mom 2 young children)
Real Estate Broker and Partner, McGuire