I'll show you bored Missy

Yesterday, my daughter decided to inform me at different times of the day that she was bored. This is even when I'd taken her downtown for fun sightseeing, to the aquarium, shopping for a toy, bought a candy stick, yadda yadda yadda. She said she was bored because in fact we were not choosing HER WAY at the aquarium. This is not the first time this summer (which is not yet a week old) that she has said this. Each time it has been preceded by an incident where she was not getting her way with her cousin and brother. I am not well equipped with the right tactics to handle this. I have an issue with escalation with her. If I 'cut her off at the quick' she can get to the storming off, "I'm leaving, never want to see you again" phase very quickly. This is quite inconvenient in public places, in open fields (when camping) and other scenarios. I threatened today that if she said it again, I'd make her sit in her room all day and then she'd understand what bored really feels like...do you think I could follow through with that? 'Prolly not! That would be punishment for us all because she'd likely howl in her room the whole time and we would cower in a corner holding our ears and rocking back and forth. Given that she is not even a pre-teen yet (or maybe she is), I am 'very afraid' about what is in store in the years to come...do you think 'mother's little helper' will come back in style again? Just kidding MOM!