Lagoon gets a lot of hate on CB, but they actually put on a pretty good Halloween event every year. You'll need to look to see if the park is open on the nights that you're planning. It tends to get crowded, but a lot of people stand in line at all the Halloween haunted houses, so you could do rides with him and maybe hit one of the "less scary" ones...

They also have a really good kids section of rides that from an amusement industry perspective is one of the best in the nation (for small, local amusement parks).