Does anyone have any other stories/advice about camping in bear country, particularly with small children?
Camping in bear country with small children is generally very safe as you can usually outrun the kids very easily!
Sorry, I just couldn't resist re-purposing that old joke.
In general, Black Bears can be somewhat stubborn, but are usually not particularly aggressive. They have an acute sense of smell and are pretty smart. They will view packaging in a car as food related, even if it's just a can of tennis balls. They also will go after perfumed or scented non-food products.
Read up on them at the Yosemite web site and pay attention to whatever information is provided at your destination.