I've heard the original Woman in Black from 1989 is terrifying, haven't seen it, though the whole thing is on youtube

The new Woman in Black is pretty solid too. Puts maintaining creepy atmosphere above jump scares, a forgotten element in a lot of horror movies these days.

I don't do scary movies much, so I have few recommendations. Take them for what they are worth:
"The Ring"
"Exorcist"-can't remember if either have been done.
Um,  can't think of any others at the moment.

I hope they choose a cheesy horror film, like Killer Clowns of outer space or puppet master, I had Cinemax and watched a lot of these as a kid.

Trick'R'Treat would be a lot of fun. I'm sure you could even find a conversation about Goosebumps in there. Same vein would be Trilogy of Terror. But. Meh.

Also:
Evil Dead 2
Interview with the Vampire
Scream

In my opinion, Jeepers Creepers is great for about the first 20 minutes then it goes nuts and a bit shite. Oddly, the second film is more fun as it doesn't really pretend to be anything it isn't. It's still shite, but it has Ray Wise, so it wins

They've already talked about Cabin in the Woods, so I'd rather they wait and not have the film take up one of these spots. There are movies they're only going to ever do as part of an October run, so let's get those out of the way before doing one they're guaranteed to get to eventually.