Making a decision on where to live is an important one. It sounds like you are not very familiar with the LA area and my advice to you would be to take a drive around the various neighborhoods so that you not only get a sense of the distance in terms of home to work and vise-versa, but you can get a sense of the location as a whole. You may like Santa Monica better than Marina Del-Rey or Long Beach over Malibu. You can browse through my website and get some statistical data on the various locations that may be of interest to you. I would be more than happy to show you around the various locations if you are not currently working with a Realtor.
Just a note, it gets very hot during the summer in the San Fernando Valley so you may not want to live there if that is an issue for you.
Wherever you live, you can split the difference between the beach and work. Santa Monica and the Palisades, directly on the coast, are nice, as are, a little bit inland, Brentwood and Mar Vista. You actually have a lot of options, depending on exactly how close to the beach you are talking about. And of course budget. (I'm wondering if you have a price in mind?)
I would look at Long Beach if I were you. Its a diverse, family friendly community with great schools & a beach. The commute to LA isn't too bad, and its much more affordable than Santa Monica or the South Bay. Email me at firstname.lastname@example.org if you would like my help.
Good luck in your new surroundings,