Transportation, traveling with kids, iPhone 4 user
The one that I've been using for years is the Embark iBART app. I just searched for it in the app store and it's the first result that pops up when I search for "bart". Super intuitive and easy to use app.
Since you're on iPhone 4, if you didn't upgrade your iOS and still have the original Google Maps, I've found their public transportion option to be very helpful, too. It extends beyond BART and includes MUNI (buses, street cars and underground ones) and cable cars.