Christmas is San Francisco is great: the weather tends to be mild (high 50s), lots of decorations and plenty of family fun!
Need to do some last minute Christmas shopping? Head over to Union Square, the shopping center of San Fran. Take a quick break in the Square to look at the giant tree or go ice skating in the park.
Food options about in the area as well. For a quick bite, head to the Cellar in the basement of Macy's for a variety of quick and tasty options. For a more iconic SF experience, head 2 blocks up Powell to Sears Fine Foods- a local institution know for their brunch. (be prepared to wait in line, especially on Sunday.) The lunch options are also yummy, especially the sandwich selection.
For a quiet afternoon, head to the San Francisco Museum of Modern Art (SFMOMA). While not great for active kids, the museum has a great introduction to modern art and includes a free audio guide. The museum store is also top-notch, with gifts for all ages.
For a more child-friendly experience, head over to the California Academy of Sciences in Golden Gate Park. The Academy combines an aquarium, a natural history museum, and a planetarium in one building. Grab a free planetarium pass to reserve a seat for one of the hourly showings. Check out the penguins, the rainforest and make sure you meet Claude, the albino alligator.
During Christmas, the Academy has special "tis the season" exhibits, including reindeer, indoor snow, and, on the day we visited, Ghiradelli chocolate was giving free chocolate and activities!
Across the a small park from the Academy is a Japanese tea garden and tea house. It's a nice place to take a break and grab some tea or snacks. Golden Gate park also has a botanical garden, children's playground and other fun activities.
For lunch, there is an a cafe in the academy, but it was such a nice day, we opted for a picnic. There is a Whole Foods market about a mile away at the eastern entrance to Golden Gate park.
Dining is one of the great wonders of San Fran. Around Union Square, check out of the historic seafood places, such as Jake's Grill or Sam's Grill.