This Sunday is San Francisco's 18th annual Spring Celebration and Easter Parade on Union Street. Running from Gough to Fillmore (on Union Street), you'll find kids' activities like bounce houses, a climbing wall, arts/crafts, a petting zoo, pony rides, and musicians. There's also a wacky Easter parade (which starts at 2:00).
While you're there, stop by the new baby boutique Sprout, a store featuring natural & organic products on Union Street.
In addition to offering nursery items and clothing, non-toxic toys etc., Sprout aims to be a family resource center, and their schedule already includes classes like pre- and post-natal yoga. mom/baby playdates and more.
Sprout is at 1828 Union Street, San Francisco. Open Monday-Saturday 10 a.m. - 7 p.m., and Sundays from 11 a.m. to 6:00 p.m. (leaving you plenty of time for brunch at the many fine eating establishments nearby).