I personally could spend hours and hours here. In fact, so could my kids! I've spent many an afternoon exploring the various exhibits here as a child and also as a parent with children.
Ryder park is where our family goes to escape the fog that hugs the coast where we live. You are almost guaranteed to find sunshine even on days when the coast is so thick in fog that you can't see the tree 100 ft in front of you. The water fountains are a huge hit with the kids especially on very hot days. However, this park always seems to be windy and can make the cold water fountains uncomfortable for young children who are already a little tentative of the water springing unpredictably from the ground.
We love to bring a picnic and spread a blanket on the well manicured grassy lawn. This playground has a fantastic group BBQ area. A perfect location for birthday parties. The bike path is flat, paved for a lot of the way, and takes you on a fantastic ride along the shoreline. Great for young children. A huge bonus for airplane lovers is being able to see airplanes coming in for their landing at SFO.
I recently took my ambling toddler to the Exploratorium and was very impressed by the scope of all the exhibits. Definitely a discovery museum geared for older children, but my toddler still had plenty of fun playing with the tornado vortex creator, the levitating bubble maker, and exploring the area on light in the back and many other exhibits.
I can't wait for him to grow up be able to enjoy some of the richer exhibits and the Tactile Dome. You have to be 7 to get into the Tactile Dome, but high schoolers even love exploring in there.
Fort Mason not only has a beautiful view of the Bay, there is just a ton of open space for your toddler to practice all their new found walking, running, rolling, turning stunts. The constant stream of dogs, bikers, kite fliers, and segway tours add plenty of visual interest for any child.
For older kids, pick up a kite to fly from the Safeway across the street. The winds are typically high coming off the Bay.
The Koret Children's Quarter is truly one of the most wonderful free playgrounds. Our 5 and 2.5 year old simply love this playground. Many of the playground structures were custom designed. This is no ordinary playground. A large wave creates a climbing wall. A tall concrete slide is a delight for kids and parents who are young at heart (like myself). The rope pyramid is challenging, but perfect for a 5 year old who loves to climb. Young children will enjoy the fantastic climbing structures and the little water play area in the sand "box"
Although this playground is almost always crowded, that adds to the energy of the playground. Parking is often very difficult on Saturday and Sunday from 10:30am onwards.
The plentiful but old school bathrooms are clean, but no changing tables were available. Nearby is a large meadow for running and the famous carousel for children is such a steal at $.50 for kids and $1.50 for adults.
Bring a picnic and enjoy the large trees that surround the playground.