A few years back large projections screens were installed at the Hollywood Bowl. This helps to get a better view no matter where you sit. Bring binoculars (or rent a pair on the grounds) for a better view.
You can bring younger children to the performances but for the most part this is an adult venue. The LA Phil does offer daytime shows suited more for children called SummerSounds for Kids.
On your way to your seats grab a few complimentary trash bags. Be sure to deposit in the correct marked barrels.
Seat cushions can also be rented for just a few dollars. Can make sitting in the wooden benches a bit more tolerable.
No matter how warm the day, the evenings just seem to get chilly. Bring a jacket.
If you take one of the Bowl busses be sure to listen to your driver. They will tell you where to pick the correct bus up when the night is over.