You know, I can't remember for sure, but I think there's a pretty nice campground right at Silverwood (like right across the street near the parking lot?) Also, there's a motel just south of the park (can't remember which one right now) that's always advertising here in Missoula on the radio...anyway, the motel has a waterpark and "fun center" attached as well. Couple guys I know have taken their families there and it got a thumbs up. I'll try to remember which one it is and post again.
-Rob