It depends on what you want to do. And how much you want to spend. I think you could stay at any major hotel downtown and be fine. That would be a good location for the Arch, baseball game, the City Museum, zoo/forest park. I *think* there's a new hotel (a drury inn maybe) right across from the zoo and near the science center. Not sure about that though--could just be my imaginiation. You could stay in clayton or Maryland Heights, but there's not a whole lot for kids that's near there. If you're thinking of something like Six Flags, there's a Holiday Inn there.