I have bunnies and kids. The kids learned quickly that rabbits are not to be picked up, only pet. They scratch a LOT just like everyone else has said. IF your kids can understand that sorta, I'd get a big bun. Even a cross bred mutt. The size will be a bit intimidating for the kids to pick up, and the bigger bone structure means they can take a little more roughness than the smaller breeds.
So, Standard Rex (may be a bit jumpy) the big lop ears, flemish giants, Champagne d'argents (my favorite-They're big, but quite willing to come up and say hello for petting) crene d'argents, maybe the silver foxes (No personal experience with them, but going by the standard of people that raise rabbits for meat don't want to lose fingers=calmer rabbits)
Stay away from anything that looks like it can run. That would be english spots, belgium hares, etc. Everything I read about them says they're a lot more active than the big buns.
And as suggested, rats are awesome! I have a trio that I've had for less than a week that I'm calming down. They're scared at first but they're great! Can check out my thread Rats! in the 'other pets' section.