I think your enjoyment with sandbox games is pretty much dependent on your imagination and creativity. I have barrels of fun on Just Cause 2, simply blowing stuff up and causing as much chaos as possible without even bothering with the story. I'll look at the time and it'll be two hours I've been doing that, it just draws me in, I can understand most people get bored though.
It's odd though, as Just Cause 2 pulls it off so well, I simply got bored doing a similiar thing in Prototype and Red Faction: Guerilla. No idea why, those games felt like they were trying to set up their own set piece moments too much, whereas Just Cause 2 just gave you some pretty crazy toys to use in a huge playground and left it up to the player to decide what to do.
I've not played it before but I've heard Saints Row 2 would be good for someone like me lol.
