ok this is what i advise doing
what my spin on everything is, if your kids are active which you mentioned over and over again (which is great because if youre not repeatative, no one gets the point and says stupid things so thank you! ), you bought the wii as a "rainy day thing" meaning its crumby outside and the kids cant go out and play their football or hide and seek or wtvr kids play (i sound old now). wii sports is great obviously for reasons you already know. i read somewhere that the action pack is BAD (no offense to anyones imput on it) that its not fit for the wii controler and it doesnt do anything except change "the look". again its what i read and i dont know from personal experience. i thought you should know that.
everyone said warioware and absolutely. ITS NOT FUN UNLESS YOU ACT IT OUT! if you sit there on the couch by yourself playing it and cheating, youre only cheating yourself out on all the fun. if your kids like "charades" type action then this is for them. its "competative" and interactive.
also, wiiplay comes out for the US any day now and that has more games just like wii sports. get out the information from IGN.com. all other games arent AS INTERACTIVE. i mean yes youre using the wiiremote but the games dont have that "get up and do something" drive like wiiplay and warioware.
i think those are your best bets personally. and you deff get a +1 in parenting since most parents dont really care if their children are active or not......
best of luck!!