TonyTib - One big item nobody has talked about: cost.
The San Francisco Museums used to have a "free" day once a month. As I remember it was the first Wednesday of the month. The idea was for local and regional residence to see what a wonderful place these were. It was also a way to get in the under represented folk who might benefit from the experience.
Usually the places would be packed with kids on field trips these days.
I find it interesting that these replies mostly focus on the greater San Francisco Bay Area museums. I had the opportunity to travel in the 1990s (and get into the back rooms and basements of some great European Museums.) Some standouts were the Deuches Museum in Munich, The British Museum, Victorian and Albert Collection, London Science Museum. All seemed to have kid friendly programs and exhibits.
Little known are the London Guildhall museum. While it took a direct hit in WWII most of the library and collections have been re-created. A lot of what is shown are the masterpieces from the guilds as well as models the apprentices made to show how things worked.
Das Museum für Musikautomaten Seewen in Switzerland, was one of the highlights of my trip in the 1990s a friend just got back from visiting it a few weeks ago and could not stop talking about it.
There is a Museum dedicated to mechanical Music also in Utrecht. They had workshops were the restorations can be seen.
My impression is that all of these have programs and days where they do outreach to the community. Planning a trip to coincide with one of these days only helps to heighten the experience. I got to have dinner and stay for a whole evening in the Victoria and Albert collection.
It is also possible to get to know the staff and curators. This can open many doors which would not otherwise be available. These people know that without educational outreach there will be no further endowments. There are many opportunities for mentoring here. I myself was mentored by people with connections to museum staffs. Why I went on these trips in the 1990s with folk twice my age. So I could learn from them before it was too late.
One big item nobody has talked about: cost. The only semi-affordable way to go to many of the top attractions is to get a family pass.
Let's look at the cost for a family with 2 elementary school children:
Cal Academy Of Sciences $120 (family membership $200)
Monterey Bay Aquarium $130 (family membership $195)
Children's Discovery Museum SJ $48 (family membership $120)
Exploratorium $96 (family membership $150)
And for San Francisco, add in the cost of getting there (gas + parking or BART+Muni/Bus; at least the CDM has cheap $5 parking nearby).
BTW, both the Exploratorium and Cal Academy had new makeovers (or new location), and IIRC, each one cost at least $500 million.
We do family memberships, but only one or two a year (this year: Cal Academy + Oakland Zoo, which offered us a great price). But since we're already paying for these memberships, and find it hard to get there enough times anyway (my goal is at least 4 visits during the membership), we're not going anywhere else (so no CDM, Aquarium, or Exploratorium this year).
Final note: the Lawrence Hall of Science is cool (my son went to a birthday party there), but it's a pain to get there if you haven't been there before.
Great picks! Once you've stopped at The Exploratorium, Chabot Space Center, and Lawernce Lab, don't forget The California Academy of Sciences in San Francisco! This place is part natural history museum, part aquarium (Steinhardt relocated here), part butterfly sanctuary, and earthquake laboratory. There are themed adult nights every Thursday, too.
I went there growing up too (East Bay kid tradition) and I remember climbing all over a life sized replica of a whale outside the museum entrance. I don't know if they still have the planetarium, but I know Chabot Space and Science Center does (and they have a lazer light show set to music!).
I don't want to be a game breaker, nor swallow too much serious pills here. But important for a museum is not to turn their place into a children's playground. That's not their task. With a bit of tears in my eyes I saw a couple of nice Dutch museums local here convert to such places. All technology ls stocked away into depots and they basically do not display much of the original technology backgrounds. "Kids find this boring", they say. But then I say: "Gleu a Mac Donalds aside the museum and let them play there!"
For people older than 16 there basically is not much to see. No real background, it is a playground. Really interesting items are hanging on the wall, high up, without sufficient interesting background. For a techie like me -at least- I recognize lots of things, but for most people it is 'abra cadabra'.
Am I child-unfriendly? No, not at all. I think that one of the main problems is to learn children to focus on one subject for longer than 5 seconds. *That* is what we should learn children first. The result will be that the museum does not *need* conversion to a playground: You can learn the child and you can learn yourself. And as soon as they get tired: Let them go to the Mac Donalds playground, leave one of the parents behind and dive back into the museum to swim & swallow into their beatiful technology ;-)