I'm thinking I'm a little late with this post, but I'll giveit anyway.
As a pet store manager, I have seen the problems with a "first pet" ofall kinds. Any small animal: hamster, gerbil, rat, guineapig, rabbit; can have their difficulties. Hamsters andGerbils are squirmy and have a tendency to bite whenfrightened. Guinea pigs are squealers and don't necessarilywant to be held (sorryto all the fans on this site, I'm justnot one). Rabbits will kick and possibly bite. Allof these are fragile and need a lot of supervision withchildren. I would actually recommend a rat if you are goingfor something small. As long as they are handled, and ofteneven if they are not, they make gentle pets. They are biggerthen a hamster or gerbil and therefore easier to handle. Theyare quieter then guinea pigs. They are just as social as arabbit, but they need less care and time. If you can get pastthe stereotype and the tail, most people absolutely lovethem. If you are willing to go with something a littlebigger, I would agree with the people who have recommended akitten. They are pretty self sufficient, litter training isbasically instinctual and taught by the mother, most are reallyfriendly and make wonderful pets for children. You just haveto watch the claws, but I feel that a rabbit can do a lot more damagewith their kicks then a cat can with scratching.
Good Luck! I think that children should be raised withanimals and it sounds like yours will have a great respect ofthem. That is what is most important.
Jen