I agree w/Iowajim

Stand for the anthem at the event I'm watching/attending. One could imagine the game stopping many times if there were more diamonds nearby. When would you finally say "OK...I can't hear anymore"

Same with parades. Most parades lead off with the American flag in some manner. You are expected to stand for that flag until it passes. The following 100+ flags shouldn't require standing unless you see a display that really touches you for some reason.