A tip that somebody told me before I had my first child, is, never let anyone tell you that you can't do something with a baby! Great tip, and, all of my kids because of that tip, I can take anywhere, and, do anything with them.
What I have learned through the years, is, that, most of the stuff I pack, I NEVER USE OR NEED. I stopped being prepared for the "just in cases" because, I never used the "just in case" stuff!
So, now, I pack a backpack with snacks and drinks, an umbrella stroller, sunblock, sunglasses, and, a hat for all my kids. I usually keep a change of clothes for the baby, and, a for the big girls, I keep extra clothes in the car.
All of my kids love noise and excitement, and, all of them have, at least once, fallen asleep in a stadium seat!
Have fun. I'm sure there will be soooo much going on, that, you will not have to worry about taking so much to keep him occupied. Take the stroller, and, walk him around as suggested below if he does start getting cranky or wants to see more! :)