How old are the kiddies? Muskegon has a pretty decent ammusement park called ... oh hell, what's it called again?? Took my class of 5th graders there when I used to teach school and even I had a riot!! Michigan's Adventure, yeah that's what it's called. Several roller coasters, many water slides, etc... You could get a hotel room in Holland, Muskegon, or Grand Haven. You might even get some OSO member to take you on a lake run (Crazyhorse has a nice big Cigarette now!!) in Muskegon. Muskegon also has the USS Silversides tied up in the channel. It's a WWII fleet submarine and is quite interesting if you or the kids are into that sort of thing.
If you need any other info feel free to ask myself or Rambunctious.