The Skirball museum is very nice, the gift shop great and the restaurant/cafe excellent (service and food). Definitely take at least one tour as the guides are informative and very knowledgeable.
The Noah's Ark is great for all, but especially for children under 10, and there is also a children's gift shop.
This museum is free every Thursday (check their website), has perfect free indoor parking, and very nice grounds with outdoor patios. Not to be missed on any tour of museums in LA.