it sounds like you have more than enough stuff to do, but its always good to have a backup plan. i like to set up a little craft table on the side, it gives the kids who dont want to take part something else to do, and its a great escape or break for shy kids. some paper plates with some of those foam self stick shapes and things like that, not too much clean up if you get self stick stuff and dont have to deal with glue, and they can do it on their own. get some of those cheap little wood boxes at the craft store for them to decorate with the foam and some markers. you can also decorate cookies or rice krispie treats with them, or make their own sundays if you dont mind the mess, or make smores, or something like that. the jumper is great, they looooove that. you can also get one of those small parachutes and some bubbles, look at oriental trading for the parachute, some bean bags or mini beach balls to bop around on it. and you can never go wrong with bubbles, though at 3, it may be tough for them to do their own, those automatic ones are a great hit (although i personally prefer old school ;) they are tons of fun) you can get some instruments and make music together, have a little parade with your party hats. you can put on some music and dance and play freeze. get some sidewalk chalk and draw roads for little toy cars, or just draw. keep it simple for the little ones. have fun :)