Depends on what activities and ambience you want. Marina Del Rey has a baby beach, called Mother's Beach, where little ones can get in the salt water without waves. It's a bit confusing to exit Marina Del Rey to get to other destinations. If you plan to go to Disneyland or other attractions, being in Santa Monica puts you closer to the freeway network. I don't know any of the specific properties you mentioned. Santa Monica has more retail, a pedestrian shopping street but with standard box stores you can find anywhere, but also many local businesses scattered around.
Planning a family vacation takes just that-planning. How large is your group? What are the kids ages? What are you looking to do?
Have you thought about staying at the MVCI timeshare property in Newport Beach? With kids, the "condo" setup is good. The kitchen is a big savings on food. Another thought would be the Residence Inn, in Anaheim. We stayed there in 2005. At the time they had a free bus to Disneyland/Califonia Adventure.