My cousin's photo album from a water park trip is full of us looking miserable and sunburned. We still laugh about it every Thanksgiving, so maybe the fails are the good stuff.
Forced fun in a sweaty crowd sounds like a family time fail to me. Real memories happen at home, not waiting in line for autographs. Maybe your sister just wants normal time with you.
Wow, that's a bummer. My friend's mom thought their anime convention trips were silly too. They went as a duo from that pirate show one year. She finally got it when she saw how happy it made him. Now she asks about the next one. Family time is what you make it.