Good children's museums in Los Angeles?

My brother and sister-in-law have a 6-month-old, and I want to get them a family membership to a children’s museum (or similar thing) for Christmas. It looks like the Children’s Museum of LA hasn’t opened yet, and the Zimmer Children’s Museum looks like it’s geared towards slightly older kids (from what I can tell from their website).

Somewhere near Santa Monica would be ideal, but I don’t think they’d mind traveling a bit if there was somewhere with really good activities for 1-year-olds… Thoughts?