A guinea pig or a hamster would be a good pet. Guinea pigs are great for kids. Well behaved kids of course. ^_^

To make sure the pet is well taken care of though, it is best, as you mentioned, for you to take it home. Not just on vacations - but on weekends too. Guinea pigs need feeding and water every day. And make sure you do your research on care, whatever pet you pick.

and chrissycat21 gave some great advice.

Good luck!