I've been the last two years in October.
It's a nice park and worth going.
Batman is just the normal B&M clone. The Screaming Eagle is a nice woodie, long, goes across the back of the park. The Ninja is fun, but kinda outdated with all the new coasters of today. Looking at the specs, the ride is 11 years old. Mr. Freeze is not running anymore, I rode it two years ago, major head banging. Too bad, this makes them lose a ride. And of coarse, The Boss is their big attraction with the 2 hour waits. This is the ride that is bringing everyone to the park, otherwise noone would go. They draw alot of local people with radio station remotes. Even in October of last year, the park was jammed.
When you drive up to the park, you see the lift hill and the first drop of The Boss, and it's mighty impressive.
They need a steal Intamin giga coaster to put them on the map again. That's what we all want in the parks that haven't been getting attention. I'm sure it will happen in a couple years. Last year they added a water park and The Boss.
While you're in St. Louis, see the Arch, you go up 600 feet and look straight down out a window. Get there early in the morning, like at 9am. Go to the arch, and the entrance is on each side. You go under, inside some buildings, then an elevator train system takes you to the top.
I'd say to find a cheap hotel downtown. You could visit Six Flags for half a day, then go downtown, see the arch, then stay in your hotel room and drive back the next day. Six Flags is located about 1 hour from the center of downtown, it's way out west.