There's an interesting article up on
The A.V. Club where Eli Roth gives his suggestions for a 24 hour marathon.
He gives an explanation for each in the article, but here's his line-up -
Noon: John Carpenter's The Thing
2pm: Zombie
4pm: The Vanishing (original Dutch version)
6pm: Pieces
8pm: The Wicker Man (1973)
10pm: Who Can Kill a Child?
Midnight: Eraserhead
2am: Suspiria
4am: Cannibal Holocaust
6am: Toby Dammit (Fellini's segment from Spirits of the Dead)
6:30am: The Evil Dead
8am: Audition
10am: Torso