Double your fun by catching Caltrain up to the city. It's a short walk along the Embarcadero from the train station up to the Exploratorium.

Parent - Great idea! We'll need to try it on a future trip.

That walk is two miles from the Caltrain Terminus to the Exploratorium, plus two miles return. Short distance perhaps for a marathon runner, but somewhat questionable with small children. Other options are the Millbrae transfer to BART followed by just a half mile walk from the Embarcadero BART Station; or practically a door-to-door connection on the Muni light rail historic streetcars (Line E) from 4th & King to Embarcadero & Green St (Pier 15/Exploratorium).

This is not the place to delve into the vagaries of public transit, but I will note that yesterday (Sunday) it was easier to simply drive, since Caltrain was way off schedule due to signaling problems, and BART had 60-minute delays with a bus-bridge between Daly City and Glen Park. Traffic on 101 was relatively light, and I had little trouble finding free street parking. Delightful afternoon and evening playing tourist in a City that people from all over the world pay good money to come visit.

Musical - I'm glad you had a great time in San Francisco. Thank you for sharing your suggestions about public transportation. We plan to wait for a train ride to the Exploratorium until the kids are a bit older- when longer walks and delays may be less challenging to deal with.

Two miles each way to the Exploratorium may not seem like much, but once you factor the amount of walking done at the museum itself makes it a sizable effort.

Remember, the typical adult will walk at about four miles per hour, so you're basically adding one hour of walking to all of your walking at the museum itself. Would you rather spend an extra hour walking inside the museum or just taking up the sights of the Embarcadero?

Better to hop onto Muni or find some sort of other motorized transportation (car sharing services, taxi, whatever) when visiting a venue that requires a lot of walking. This is not the case when the destination is more about a seated experience (movies, theater, sporting events, etc.).

This is an individual judgment call. You can't just look at a map and make the call. You need to think about what you are going to do at the destination itself.

Reader - Yes, I've walked it without kids and it can be nice to stop at places along the way, like the Ferry Building. But the Exploritorium also has so much to see and do. Definitely nice to have a variety of options. Thanks for commenting!