You mean Pier 39. 49 is an industrial location I believe
Coit tower up on telegraph hill is nice
Golden gate park, SF zoo (Tell your kids the tigers only eat the bad children), and Metreon will give your kids spazzy run-around time

How old are your kids? If they're boys around 8-12, you should check out the USS Pampanito WWII submarine. Alcatraz is actually kinda cool too.