At 15 and 11, those guys have probably seen worse on MTV! Bourbon Street is only one small part of the French Quarter - everybody should see the street performers around Jackson Square, the riverfront, and all the other sights - not bad food around there either. Check out Johnny's Por Boys or Mother's for an economical belly full of local fare.
On the way out of town, take Route 90 rather than I-10. It will take you out past the levees and run you up the coast through Biloxi - a little longer than I-10, but much more scenic. The water really doesn't get nice and blue until you hit Florida, but it is a nice ride.